Service Manual
N-20/N-20P N-20/N-20P P ortabl ortable e Pul P ulss e Oximet Ox imeter er
Tyco Healthcare Group LP Nellcor Puritan Bennett Division Division 4280 Hacienda Drive Pleasanton, CA 94588 USA Toll Free 1.800.NELLCOR Authorized Representative Tyco Healthcare UK LTD 154 Fareham Road Gosport PO13 0AS, U.K.
Tyco Healthcare Group LP Nellcor Puritan Bennett Division Division 4280 Hacienda Drive Pleasanton, CA 94588 USA Toll Free 1.800.NELLCOR Authorized Representative Tyco Healthcare UK LTD 154 Fareham Road Gosport PO13 0AS, U.K.
CONTENTS
1
2
3
Introduction ............................ .......................................... ............................ ............................ ............................ ............................ ............................ ............................ .......................... ............ 1-1 1.1
Manual Overview ........................... ......................................... ............................ ............................ ............................ ............................ ............................ ............................ ................. ... 1-1
1.2
......................................... ............................ ............................ ............................ ............................ ............................ ..................... ....... 1-1 Warnings and Cautions ...........................
1.3
Description of N-20 Portable Pulse Oximeter Oximeter ............................ .......................................... ............................ ............................ .......................... ............ 1-1
Routine Maintenance ........................... ......................................... ............................ ............................ ............................ ............................ ............................ ..................... ....... 2-1 2.1
......................................... ............................ ............................ ............................ ............................ ............................ ............................ ............................ ................. ... 2-1 Overview ...........................
2.2
Cleaning ............................ .......................................... ............................ ............................ ............................ ............................ ............................ ............................ ............................ ................. ... 2-1
2.3
........................................ ............................ ............................ ............................ ........................ .......... 2-1 Periodic Safety and Functional Functional Checks ..........................
2.4
Battery........................... ......................................... ............................ ............................ ............................ ............................ ............................ ............................ ........................... ..................... ........ 2-1
Performance Verification ........................... ......................................... ............................ ............................ ............................ ............................ .......................... ............ 3-1 3.1
Introduction ........................... ......................................... ............................ ............................ ............................ ............................ ............................ ............................ .......................... ............ 3-1 Required Materials
CONTENTS
8
9
7.1
General Instructions ........................... .......................................... ............................. ............................ ............................ ............................. ............................. ........................ .......... 7-1
7.2
.......................................... ............................ ............................ ............................ ............................ ........................ .......... 7-1 Repacking in Original Carton............................
Specifications ............................ .......................................... ............................ ............................ ............................ ............................ ............................ ............................ ........................ .......... 8-1 8.1
......................................... ............................ ............................ ............................ ............................ ............................ ............................ ............................ ................... ..... 8-1 Readout ...........................
8.2
Controls ............................ .......................................... ............................ ............................ ............................ ............................ ............................ ............................ ............................ ................. ... 8-1
8.3
Operating Modes............................ .......................................... ............................ ............................ ............................ ............................ ............................ ............................ ................. ... 8-1
8.4
.......................................... ............................ ............................ ............................ ............................ ............................ ............................ ..................... ....... 8-2 Printer Output ............................
8.5
N-20/N-20P Performance............................ .......................................... ............................ ............................ ............................ ............................ ............................ ................. ... 8-2
8.6
.......................................... ............................ ............................ ............................ ............................ ............................ ............................ ........................ .......... 8-3 Sensor Types ............................
8.7
Electrical Specifications Specifications ............................ .......................................... ............................ ............................ ............................ ............................ ............................ ................... ..... 8-3
8.8
.......................................... ............................ ............................ ............................ ............................ ........................ .......... 8-3 Environmental Specifications Specifications ............................
8.9
Physical Specifications Specifications ............................ .......................................... ............................ ............................ ............................ ............................ ............................ ..................... ....... 8-4
Technical Supplement ........................... ......................................... ............................ ............................ ............................ ............................ ............................ ................... ..... 9-1 9.1
......................................... ............................ ............................ ............................ ............................ ............................ ............................ ............................ ................. ... 9-1 Overview ...........................
9.2
Functional versus Fractional Saturation Saturation ........................... ......................................... ............................ ............................ ........................... ..................... ........ 9-1
CONTENTS Figure 9-7: Printer Control Block Diagram....................................................................................................... 9-5 Figure 9-11: Variable Gain Circuit.................................................................................................................... 9-9 Figure 9-12: Filtering Circuit............................................................................................................................ 9-10 Figure 9-4: Digital Circuitry Block Diagram.................................................................................................... 9-12 Figure 9-14: N-20 Hardware Block Diagram................................................................................................... 9-14 Figure 9-15: Address Demultiplexing Circuit .................................................................................................. 9-15 Figure 9-16: Address Decoding Circuit............................................................................................................ 9-16 Figure 9-17: CPU Memory Circuit ................................................................................................................... 9-17 Figure 9-18: Input Port Circuit......................................................................................................................... 9-18 Figure 9-20: Real-Time Clock Circuit .............................................................................................................. 9-19 Figure 9-21: Audio Output Circuit ................................................................................................................... 9-20 Figure 9-6: Display Control Block Diagram.................................................................................................... 9-20 Figure 9-23: User Controls Circuit................................................................................................................... 9-22 Figure 9-26: Analog Reference Voltage Circuit............................................................................................... 9-25 Figure 9-27: Ambient Light Circuit.................................................................................................................. 9-25 Figure 9-28: Ambient Temperature Circuit..................................................................................................... 9-26 Figure 9-29: Battery Voltage Circuit ................................................................................................................ 9-26 Figure 9-30: Battery Type Circuit .................................................................................................................... 9-26 Figure 9-32: Printer Flex Circuit ...................................................................................................................... 9-28 Figure 9-8: LED Drive Circuit ......................................................................................................................... 9-31 Figure 9-9: Differential Synchronous Demodulation Circuit........................................................................ 9-33 Figure 9-10 N-20 HSO Timing Diagram ......................................................................................................... 9-35 Figure 9-13: AC Variable Gain Control Circuits............................................................................................ 9-37 Figure 9-19: Output Port Circuit...................................................................................................................... 9-39 Figure 9-22: Display Control Circuit................................................................................................................ 9-41 Figure 9-24: Power Supply Circuit................................................................................................................... 9-43 Figure 9-25: Power Control Circuit.......... 9-45
1
INTRODUCTION
1.1 Manual Overview 1.2 Warnings and Cautions 1.3 Description of the N-20 Portable Pulse Oximeter
1.1
Manual Overview This manual contains service information for the Nellcor ® portable pulse oximeter, models N-20/N-20P, that is necessary to maintain and repair the N-20/N-20P by qualified service personnel. Note that models designated for sale in Europe differ from models designated for sale in the USA only in that the user control buttons and display use icons rather than alphabetical characters, and that the product labels reflect the appropriate European certifications and company addresses.
1.2
Warnings and Cautions "WARNING" is used to call attention to procedures that could result in an error in calibration or performance, and/or precautions that are important to ensure the safety of both service personnel and patients. "CAUTION" is used to call attention to procedures that should be carefully followed to prevent damage to the instrument.
1.3
Description of N-20 Portable Pulse Oximeter
2
R OUTI OU TIN N E MA I N TE N A NC E
2.1 Overview 2.2 Cleaning 2.3 Periodic Safety and Functional Checks
2.4 Battery
2.1
Overview The N-20/N-20P requires no routine maintenance, routine service, or calibration. If service is necessary, contact qualified service personnel or Nellcor’s representative. Use only Nellcor-approved test equipment when running a performance test on the N-20/N-20P. The user's institution and/or local or national agencies may require testing.
2.2
Cleaning Dampen a cloth with a commercial, commercial, nonabrasive cleaner, and lightly wipe the surfaces of the N-20/N-20P. Do not spray or pour liquid on the instrument instrument or accessories. Do not allow liquid to contact connectors, switches, or openings in the chassis.
2.3
Periodic Safety and Functional Checks The following checks should be performed at least every 2 years by a qualified service technician.
3
P E R F OR MA NC E V E R I F IC A TION TI ON
3.1 Introduction 3.2 Required Materials 3.3 Performance Tests
Caution: Adhere Adhere to all testing instructions; failure failure to do so may damage the N-20/N-20P.
3.1
Introduction This section describes performance verification for the N-20 and N-20P pulse oximeters (hereafter called the “monitor”), following repairs. The N-20/N-20P are powered by alkaline batteries. The N-20/N-20P design includes built-in electrical electrical insulation; no ground resistance resistance or electromagnetic electromagnetic leakage testing is required. The tests can be performed without removing the monitor cover. If the monitor fails to perform as specified in any test, repairs must correct the discrepancy before the monitor is returned to the user.
3.2
3.3
Required Materials Durasensor
Nellcor DS-100A
Tester, Pulse Oximeter
Nellcor SRC-2
Performance Tests
Performance Verifi cation
N-20 (no printer)
37 hours with Alkaline batteries.
N-20/P (with printer)
32 hours with Alkaline batteries.
This test requires a new set of batteries. The new batteries must be installed after the test. Connect the Nellcor SRC-2 pulse oximeter tester to the monitor. Set the switches on the SRC-2 as follows: Switch Setting RATE
38
LIGHT
LOW
MODULATION
LOW
RCAL/MODE RCAL 63/LOCAL Momentarily press the MEASURE button, and verify the following power-up sequence: All indicators—OXYGEN SATURATION, PULSE RATE, PULSE SEARCH, LOW BATTERY, and the PULSE BARS—light for a few seconds. Verify the OXYGEN SATURATION, and PULSE RATE displays indicate "888.” The OXYGEN SATURATION display momentarily indicates the monitor 3-digit software version. The other displays are not lit. Software versions may vary depending on the type of monitor and the date of manufacture. The N-20P will display printer status immediately after displaying the software version. The OXYGEN SATURATION display will indicate “Pr”and the PULSE RATE display will indicate either “On” or “OFF.” The OXYGEN SATURATION display momentarily indicates the letters ”tSt” and the monitor sounds
Performance Verifi cation
During the next few seconds, the instrument: • • •
Switches off the display backlight; Displays three digits in the Oxygen Saturation display field representing the software version (for example, 123 is software version 1.2.3). Only the N-20P displays the printer status in the display fields; that is, either "Pr On" or "Pr OFF."
If a sensor is attached to the instrument, a zero ("0") appears in first position of the display fields. The Pulse Search indicator flashes; if no sensor is attached to the instrument, horizontal dashes appear in all six Oxygen Saturation and Pulse Rate display fields, and the Pulse Search indicator flashes. After approximately 1 minute, a short beep occurs and the instrument automatically switches off. If at any time during the test sequence "Err" followed by a code number is displayed, make a note of the error code and refer to Section 4.7, Error Codes, for a description. 3.3.3.1 How To Run the Self-Test
Place a new set of batteries in the monitor. Do not connect a sensor or SRC-2 to the monitor. Momentarily press the MEASURE button, verify the following power-up sequence: All indicators—OXYGEN SATURATION, PULSE RATE, PULSE SEARCH, LOW BATTERY, and the PULSE BARS—light for a few seconds. Verify that the OXYGEN SATURATION and PULSE RATE displays indicate "888."
Performance Verifi cation
ADV D/D combinations 1. 2.
3.
Ad dd Err
Press the Measure button: "9O" appears in the Oxygen Saturation display. Press the Battery-Check button: "bAt" appears in the Oxygen Saturation display.
Press the printer ON button: "On" appears in the Oxygen Saturation display. A printer test pattern prints out; the following is an approximate example of the test pattern:
Examine the test pattern to verify that all dots print with a uniform darkness. Overall printout darkness can be adjusted; to adjust printer darkness, see paragraph 4.6.7. If printout darkness is
Performance Verifi cation
4.
5. 6.
All indicators—OXYGEN SATURATION, PULSE RATE, PULSE SEARCH, LOW BATTERY, and the PULSE BARS—light for a few seconds. Verify that the OXYGEN SATURATION and PULSE RATE displays indicate "888.” The OXYGEN SATURATION display momentarily indicates the monitor 3 digit software version. The other displays are not lit. Software versions may vary depending on the type of monitor and the date of manufacture.
The N-20P will display printer s tatus immediately after software version display. The OXYGEN SATURATION display will indicate “Pr,” and the PULSE RATE display will indicate either “On” or “OFF.” The OXYGEN SATURATION display momentarily indicates the letters ”tSt” and the monitor sounds a single tone. The other displays are not lit. “tSt” verifies that the monitor recognizes that a tester is connected. The OXYGEN SATURATION and PULSE RATE displays indicate “0,” the PULSE SEARCH indicator is flashing, and the PULSE BAR will start to register the simulated pulse. After a few beats a pulse tone will be heard, and the PULSE SEARCH indicator will turn off. The OXYGEN SATURATION display indicates between 79 and 83 and the PULSE RATE display indicates between 37 and 39.
3.3.6.2 Normal Operation
These tests are an overall qualitative check of the system and require connecting a live subject to the monitor:
Performance Verifi cation
TEST RESULTS
Model:
N-20
Serial:_____________________________
Date:___________Customer Name:________________________________
Description
Pass
Fail
Performance Tests
_____
____
Backlight Test
_____
____
Battery Performance
_____
____
Testing the Low Battery Indicator
_____
____
Power-Up Performance
_____
____
How to Run the Self-Test
_____
____
Printer Test
4
TROUBLESHOOTING
4.1 How to Use This Section 4.2 Who Should Perform Repairs 4.3 Replacement Level Supported 4.4 Obtaining Replacement Parts 4.5 Troubleshooting Guide 4.6 Service Procedures 4.7 Error Codes
WARNING: Disassembly of the instrument exposes hazardous voltages. To avoid injury or instrument damage, disassembly or maintenance must be attempted only by qualified service personnel.
4.1
How to Use this Section This section explains how to identify and correct monitor difficulties and provides procedures for common service-related activities, such as battery replacement, clearing paper jams, and adjusting printer darkness. Use this section in conjunction with Section 3, Performance Verification, and Section 6, Spare Parts.
Troubleshooting
4.5
Troubleshooting Guide This section discusses potential symptoms, possible causes, and actions for their resolution. Should this troubleshooting guide fail to address the symptoms evident in a particular N-20/N-20P, please contact Nellcor's Technical Services Department or a local Nellcor representative for assistance. If the N-20/N-20P does not perform as expected: • • •
Check for proper sensor placement. Depending on concentration, indocyanine green, methylene blue, and other intravascular dyes may affect the accuracy of a measurement. These instruments are calibrated to read oxygen saturation of functional arterial hemoglobin (saturation of hemoglobin functionally capable of transporting oxygen in the arteries), and significant levels of dysfunctional hemoglobins such as carboxyhemoglobin or methemoglobin may affect the accuracy of a measurement.
If the electronics and/or display functions require testing, refer to Section 3, Performance Verification.
Symptom 1: No response to Measure button. Cause
Action
Battery access door may not be properly latched.
Check access door and ensure it is properly latched.
Batteries may be discharged.
Exchange them for a new set.
Batteries may be incorrectly installed.
Ensure that batteries are oriented according
Troubleshooting
Symptom 2: Pulse Search indicator appears for more than 5-10 seconds. Cause
Action
Sensor may be improperly positioned.
Ensure the sensor is correctly applied (see sensor directions for use).
Incorrect sensor may be in use.
See sensor directions for use to ensure that the patient's weight and sensor application is correct. Test the sensor on another person to verify proper operation.
Perfusion may be too low.
Check patient status. Test the instrument on someone else, or try another type of sensor. The N-20/N-20P will not make a measurement if perfusion is inadequate.
Foreign material on the sensor LEDs or photodetector may be affecting performance.
Clean the test area and ensure that nothing blocks the sensor site.
Patient motion may be interfering with the instrument's ability to find a pulse pattern.
If possible, ask the patient to remain still. Verify that the sensor is securely applied and replace it if necessary, move it to a new site, or use a sensor that tolerates patient movement, such as an appropriate adhesive sensor.
Environmental motion may be interfering with the instrument's ability to track a pulse The sensor may be too tight, there may be excessive illumination (e.g., a surgical or bilirubin lamp or direct sunlight), or the sensor may be placed on an extremity with a blood pressure cuff, arterial catheter, or intravascular line.
Troubleshooting
Cause The printer is not operational, but the N-20P continues to obtain patient measurements.
Symptom 6:
Action Check to see if the paper is jammed. Examine the print head and ensure that it has returned to the home position.
Err followed by a number appears on the display. Cause
See Section 4.7 for error codes.
Symptom 7:
Action Record the number that is displayed.
Time or date is incorrect (N-20P only). Cause
The real-time clock (RTC) battery may be exhausted.
Action Replace the RTC battery (see Section 4.6.4). Reset the time and date (see Section 4.6.3).
Symptom 8:
Printer fails to operate (N-20P only). Cause
Fuse F2 on the auxiliary PCB may be open.
Action See paragraph 4.6.5 for information about fuses.
Troubleshooting
4.6.1
Installing Batteries
1. 2. 3. 4.6.2
Remove the battery cover access door by pressing the battery compartment access door latch.
Install four alkaline "C" cell batteries. Be sure to observe the polarity indicator sticker. Replace the battery cover access door.
Loading/Clearing Printer Paper
The N-20P uses a thermal paper that can show printed characters on one side only. Make sure that the paper roll is correctly installed; always refer to the graphical instruction label found on the paper roll. 1. 2. 3. 4.
Press down and outward on the top of the paper compartment door to remove it. Feed the paper into the paper compartment slot; refer to the graphic label for orientation. Press and hold the ADV button until the end of the paper appears at the paper exit slot. Replace the paper compartment door.
If the paper jams either during the loading process or during printing, proceed as follows: 1. 2.
3.
4.
Remove both the paper door and the printer-head access cover. Firmly grab and pull the paper roll backward—out and away from the print head—observe the access to the print head to determine whether or not the paper escaped from the jammed position. If paper remains jammed between the print head and printer, press the ADV button; the jammed paper may work its way out. If the paper remains jammed, and the printer drive does not advance the paper, manually advance the drive gear on the side of the printer to free the paper. If these attempts fail to free the jammed paper, remove the printer from the unit to gain full access (see paragraph 5.3, N-20 Disassembly Procedure).
Troubleshooting
13.
4.6.4
Date and time are now correct. Check by switching on the N-20P with the printer enabled. After the N-20P executes its Power-On Self-Test, the printer prints the spot check mode header with the correct date and time.
Replacing the Real-Time Clock (RTC) Battery
The socket for the RTC battery (BT1) is located on the auxiliary PCB at grid location 5D. Typical life of the clock battery is 5 years. 1. 2. 3. 4. 5. 4.6.5
Disassemble the N-20 (see Section 5.3, N-20, Disassembly Procedure). Using a thin flathead screwdriver, gently pry the RTC battery from its socket. Insert a new battery into the socket, observing the polarity indication (socket's clip and battery's flat side are positive). Reassemble the unit. Reset the clock (see paragraph 4.6.3, Setting Date and Time).
Replacing Fuses
Two fuses (F1 and F2) are located on the auxiliary PCB. Fuse F1 may open to protect the CPU and its associated components from damage if the power supply malfunctions. Fuse F2 may open to protect the printer from damage due to excessive voltage if the printer head jams or has been physically damaged. Refer to the auxiliary PCB schematic for the locations of F1 and F2. 4.6.6
Replacing the DB-9 Connector
1. 2.
Disassemble the N-20 (see Section 5.2); the connector is on the main PCB at grid location 3A. Using a low-power soldering iron, unsolder the connector from the PCB and remove it. Save all Teflon tubing, ferrite blocks, and insulating materials for the replacement connector.
Troubleshooting
Note: The parenthetic line description is not printed, and button presses are ignored whenever the printer is printing. 1.
Press the ADV button to change the darkness setting. The printer prints a line with each button press, and the setting increments from lighter to darkest and then wraps back to lighter. 2. Allow the N-20P to switch off (about 30 seconds). The last print darkness setting is remembered when the N-20P is switched back on. Test this by repeating the procedure and skipping step 3.
4.7
Error Codes If a failure is detected during the Power-On Self-Test or during any performance test, the error message (Err) appears in the Oxygen Saturation display and a 3-digit error code number appears in the Pulse Rate display. If an error message appears, find its category (the first digit of the error code represents the category) and record the error code number. Match the number to the description in the following table, and contact Nellcor's Technical Services Department or Nellcor's local representative for assistance. Internal tests are performed in the order of the table listing. The first error condition encountered is the one displayed.
4.7.1
Category 1 — Microprocessor Errors
Table 4-1: Microprocessor Error Codes Errors in the CPU (main PCB). Likely action is replacement of the CPU. 101
Error in internal RAM registers test
102
Error in zero register test
Troubleshooting
4.7.3
Category 3 — PROM Errors
Errors in PROM memory (main PCB). Likely action is replacement of the PROM. 301 4.7.4
Error in PROM test
Category 4 — I/O Port Errors
Errors in the CPU's internal I/O port (main PCB). Likely action is replacement of either the CPU or the main PCB. 401–409
Errors in I/O port test
4.7.5
Category 5 — Reserved
4.7.6
Category 6 — Clock Errors
Failure of the real-time clock (auxiliary PCB), or timing differences between the CPU’s clock and the real-time clock. Likely action is replacement of the main or auxiliary PCB.
4.7.7
601
Failure of real-time clock
602, 603
Errors in real-time clock
Category 7 — Watchdog-Timer Errors
Error in the watchdog-timer circuit of the CPU (main PCB). Likely action is replacement of the CPU. 701, 702
Errors in watchdog-time
5
DIS A S S E MB LY G UIDE
5.1 Introduction 5.2 Required Equipment/Tools 5.3 N-20 Disassembly Procedure 5.4 N-20P Disassembly Procedure
WARNING: Only qualified service personnel must perform repair and testing. Improper repair and/or adjustment may compromise patient safety or the accuracy of the instrument.
5.1
Introduction The N-20/N-20P can be disassembled down to all major component parts, including: • • • •
PCBs battery cables chassis enclosures
WARNING: Before attempting to open or disassemble the N-20/N-20P, disconnect the power cord. Caution: Observe ESD (electrostatic discharge) precautions when working within the unit.
Dis as s embly G uide
20
21
34
19
Figure 5-1: Sensor Lock, and Printer, Paper, and Battery Access Doors 1. 2. 3.
Remove the battery door (19) and batteries. Remove the sensor lock (34) by lightly pressing in on its ears and pulling out from the sensor shroud. Remove the paper door (20) and paper roll, and the printer door (21).
Dis as s embly G uide
5.2.2
Removing the Covers
16
18
27 26
Dis as s embly G uide
5.2.3
Removing the PCBs and Display Assembly
Tab #1
Tab #3
18 Detail B
Flex #1
6
Tab #4 Tab #2 Flex #3
Flex #2 Detail A 5
27 11 12 13 26
Figure 5-3: Main, Auxiliary, and Display PCB Assembly 1. 2.
Remove the Measure button (6) from the main PCB. Remove the entire PCB/Taliq display assembly from the rear cover by tilting opposite the
Dis as s embly G uide
5.2.5
Disassembling the Printer/Flex Circuit Assembly 29 32
4
7
37
28
6
SPARE PARTS
6.1 N-20/N-20P Spare Parts
6.1
N-20/N-20P Spare Parts To order replacement parts, contact Nellcor's Technical Services Department and order by part number. Item numbers correspond to the callout numbers in the figures. Item
Designator
Description
P/N
1
SW1
Battery switch (auxiliary PCB)
630106
2
BT1
Battery holder (auxiliary PCB)
901582
3
BT1
Battery, lithium (auxiliary PCB)
640112
4
Bracket, printer, hold-down
023133
5
Button, battery-check
023301
Button, measure
022948
Button, measure (European version)
026386
Buttons, printer, strip
022947
Buttons, printer, strip (European version)
026387
Connector shield, DB-9
023467
Connector, DB-9
463103
6
S2
7 9 10
P1
S pare Parts
Item
Designator
Description
P/N
31
Screw, captive
891324
32
Screw, Phillips, 4-40 ×1/4
801025
33
Screw, plastite
871031
34
Sensor lock
022943
35
Sensor shroud
022944
36
Spacer
023452
37
Stiffener, printer button
023131
38
Tape, foam (.88" ×.38")
023300
Transducer, audio, piezo ceramic
691230
39
BZ1
7
PAC K ING FOR SHIPME NT
7.1 General Instructions 7.2 Repacking in Original Carton 7.3 Repacking in a Different Carton
Should you need to ship the N-20/N-20P monitor for any reason, follow the instructions in this section.
7.1
General Instructions Pack the monitor or printer carefully. Failure to follow the instructions in this section may result in loss or damage not covered by the Nellcor warranty. If the original shipping carton is not available, use another suitable carton or call Nellcor Technical Services to obtain a shipping carton. Prior to shipping the device, contact Nellcor Technical Services for a returned goods authorization (RGA) number. Mark the shipping carton and any shipping forms with the RGA number.
7.2
Repacking in Original Carton If available, use the original carton and packing materials. Pack the monitor or printer as follows: Place the monitor, or printer, and, if necessary, accessory items in original packaging. Place in shipping carton and seal carton with packing tape. Label carton with shipping address, return address, and RGA number.
8
SPECIFICATIONS
8.1 Readout 8.2 Controls 8.3 Operating Modes 8.4 Printer Output 8.5 N-20/N-20P Performance 8.6 Sensor Types 8.7 Electrical Specifications 8.8 Environmental Specifications 8.9 Physical Specifications 8.10 Quality Information
8.1
Readout Display shows SpO2 (saturation of arterial hemoglobin oxygen), pulse rate, and pulse amplitude; also included are a Pulse Search and Low Battery indicator, and an electroluminescent backlight.
8.2
Controls
8.2.1
N-20
The Measure button switches the instrument on and off, and initiates the measurement cycle.
S peci fications
For the N-20, a 2% or greater decrease in SpO2 is indicated by two brief, low-pitched tones. The N-20P printout shows SpO2 and pulse rate at 30-second intervals. For the N-20P, a 2% or greater decrease in SpO2 is indicated by two brief, low-pitched tones and an asterisk (*) on the printout. At the end of the measurement period, a header and statistical summary values (minimum, maximum, and mean of both pulse rate and oxygen saturation) are printed.
8.4
Printer Output When activated by the printer ON button, the N-20P output shows date, time, SpO2, and pulse rate (in spot check mode), with space provided for writing in patient identification. The thermal paper printout measures roughly 40 mm (1.6 in.) by 100 mm (4.0 in.) in size. If the N-20P is in spot check mode and the printer is turned on any time during a measurement or after a measurement is taken and before the N-20P powers down, the printer will catch up and print a complete record of the measurements recorded up to the current moment.
8.5
N-20/N-20P Performance
8.5.1
Range
8.5.2
Saturation:
0–100%
Pulse Rate:
20–250 beats per minute (bpm) ± 1 standard deviation
SpO2 Accuracy
1
S peci fications
8.6
Sensor Types Table 8-1: Sensors Sensor
Model
Patient Size
Oxisensor II oxygen transducers (sterile, single-use only)
N-25/N-25LF I-20/I-20LF D-20 D-25/D-25L R-15
<3 or >40 kg 3 to 20 kg 10 to 50 kg >30 kg >50 kg
Oxiband oxygen transducer (reusable with disposable nonsterile adhesive)
OXI-A/N OXI-P/I
<3 or >40 kg 3 to 40 kg
Durasensor oxygen transducer (reusable, nonsterile)
DS-100A
>40 kg
Nellcor reflectance oxygen transducer (reusable, nonsterile)
RS-10
>40 kg
Dura-Y multisite oxygen transducer (reusable, nonsterile)
D-YS
>1 kg
D-YSE
>30 kg
D-YSPD
3 to 40 kg
For use with the Dura-Y sensor: Ear clip (Reusable, nonsterile) Pedi-Check ™ pediatric spot-check clip (reusable, nonsterile)
S peci fications
8.8.2
Storage Temperature
-20 to 50 °C (4 to 122 °F)
8.9
Humidity:
Any humidity/temperature combination without condensation
Altitude:
0 to 6200 meters (0 to 20,000 ft)
Physical Specifications Physical specifications are based on product without the protective boot.
8.9.1
8.9.2
Weight (with batteries installed)
N-20:
0.6 kg (1.3 lb)
N-20P:
0.62 kg (1.4 lb)
Dimensions
N-20:
19.0 cm high ×7.6 cm wide ×5.08 cm deep (7.5 in. ×3.0 in. ×2.0 in.)
N-20P:
19.0 cm high ×7.6 cm wide ×6.35 cm deep (7.5 in. ×3.0 in. ×2.5 in.)
8.10 Qualifying Information
9
TECHNICAL SUPPLE ME NT
9.1 Overview 9.2 Functional versus Fractional Saturation 9.3 Measured versus Calculated Saturation 9.4 Circuit Analysis 9.5 Functional Overview 9.6 Definition of Terms 9.7 Overall Block Diagram 9.8 SpO2 Analog Circuit 9.9 Digital Circuitry 9.10 Circuit Illustrations
9.1
Overview The N-20/N-20P is based on the principles of spectrophotometry and optical plethysmography. Optical plethysmography uses light absorption technology to reproduce wave forms produced by pulsatile blood. The changes that occur in the absorption of light due to vascular bed changes are reproduced by the pulse oximeter as plethysmographic wave form. Spectrophotometry uses various wavelengths of light to qualitatively measure light absorption through given substances. Many times each second, the N-20/N-20P passes red and infrared light into
Techni cal Supplement
Figure 9-1 illustrates the effect that variations in pH, temperature, partial pressure of carbon dioxide (PCO2), and concentrations of 2,3-DPG and fetal hemoglobin may have on the oxyhemoglobin dissociation curve.
Figure 9-1: Oxyhemoglobin Dissociation Curve
Techni cal S upplement
Main PCB
Patient sensor
SpO2 analog Microprocessor Memory Display control Sensors: temperature ambient light battery voltage
PROM
Measure button
20-pin headers
Auxiliary PCB Power supply Printer interface Display control Audio beeper
Batteries
4-6 VDC
Realtime clock
Flex connectors
Check battery button
Display backlight
Printer flex circuit
Printer
N-20P only
Figure 9-2: Overall Block Diagram 9.6
SpO2 Analog Circuitry Block Diagram (Figure 9-3) Analog circuitry has high signal sensitivity and reduced susceptibility to noise. Its design allows for a
Techni cal Supplement
9.6.1
Digital Circuitry Block Diagram (Figure 9-4)
Figure 9-4 shows the N-20/N-20P hardware and circuits, which include the CPU and system memory, the power supply and power control circuitry, user controls, display and ambient light sensors, audio output, thermal printer (N-20P only) and ambient temperature sensor, and the real-time clock.
Measure Check Battery
Power supply & control
N-20/N-20P Control buttons
AUX PCB
Ambient light sensor
Main PCB AUX PCB
CPU
Display drivers
Main PCB Memory & software
Display
Audio beeper
AUX PCB (N-20 only)
Printer
To analog section Real-time clock
AUX PCB
Ambient temp. sensor
Main PCB
ON
ADV
D/D
Printer Control button
Techni cal S upplement
9.6.3
Display Control Block Diagram (Figure 9-6)
The N-20/N-20P display is controlled by the display control circuitry (see Figure 9-6). A sensor is used to measure ambient light. During low light conditions, the display backlight, an electroluminescent device, is automatically switched on. Main PCB
Microprocessor
Main PCB
AUX PCB
Control conditioning circuit (generates timing signals)
Display driver (1) Display Display driver (2)
Display backlight
AUX PCB High voltage control circuit (enables +70 VDC to display)
70 volts
Figure 9-6: Display Control Block Diagram 9.6.4
Printer Control Block Diagram (Figure 9-7)
Printer circuitry (Figure 9-7) is divided into two subsections: the printer interface and the printer flex circuit. The printer interface circuitry is present on all models, but is disabled by software in the N-20. The printer flex circuit is added when a printer is present.
Techni cal Supplement
9.7.4
High Speed Outputs (HSO)
The 6 HSO lines control most of the timing of the LED signal pulse and the demodulation of the received signal. 9.7.5
Input and Output (I/O)
Input and Output (I/O) are digital lines that are used by the CPU to read in data and output data. 9.7.6
Light-Emitting Diodes (LEDs)
Two LEDs are used in Nellcor oximetry sensors. Light is transmitted through body tissue and received by a photodetector circuit that converts it to photocurrent. The two wavelengths, which are used for calculation of pulse rate and oxygen saturation in blood, are transmitted at the following frequencies: • •
9.7.7
infrared (IR) light at approximately 915 microns red light at approximately 660 microns
Pulse Width Modulation (PWM)
The three 8-bit PWM outputs can be software controlled; their duty cycle can be changed from 0-255/256 of the total pulse duration. PWM frequency is the crystal frequency of the CPU, which is 10 MHz divided by 1024. The PWMs control the gains within the analog circuit. 9.7.8
RCal
Sensor RCal value is a resistance value specific to an individual sensor. This value is used by the
Techni cal S upplement
9.9
SpO2 Analog Circuitry This subsection describes the SpO 2 analog hardware. The analog circuitry has high signal sensitivity and reduced susceptibility to noise. Its design allows for a wide range of input signal levels and a broad range of pulsatile modulation. The SpO2 analog block diagram (Figure 9-3) consists of four subsections:
9.9.1
Sensor Output/LED Control
The CPU controls the gain of both LEDs so that signals received at the input amplifier are within an acceptable dynamic range. Signal channel gain may also need to be increased. The CPU uses PWM lines to control LED current level or to amplify the signal channel. 9.9.2
Input Conditioning
Sensor output current is converted to voltage. A demodulation circuit minimizes the effects of other light sources and stray frequency inputs. Because the IR and RED signals are at different current levels, the two LED signals are demultiplexed and separately amplified, so they can be compared with each other. Two circuits handle the demultiplexing by alternately selecting LED signals using switches. Filters then remove noise and smooth the signals before sending them to the amplifiers. 9.9.3
Signal Gain
The separated LED signals are amplified so that their current levels are within the A/D converter's acceptable range. The signals are filtered to improve the signal-to-noise ratio, and clamped to a
Techni cal Supplement
9.9.5.1 LED Drive Circuit
The LED drive circuit is illustrated in Figure 9-8 (at the end of this section). The IR and red LEDs are separately controlled with their drives’ currents multiplexed over two shared wires. Current to the IR LED is in the range of 4.3-50.0 mA; and, current to the red LED is in the range of 6.5-75.0 mA. Currents are limited to less than 100 mA for two reasons: (1) slight excess current can potentially change the emission characteristics of the LEDs, and (2) large excess current could create excessive heat at the sensor site. The IR/red LED transmission signal (HSO1 of the CPU) is fed into the select inputs of the triple single-pole-double-throw (SPDT) analog multiplexing switch U10, causing either the IR or the red LED transmission to be enabled.
PWM1, which is filtered by the network of R44, C37, R52, and C38, is input to the LED drive circuit switch U10, and controls the magnitude of the IR LED current supply. PWM2, which is filtered by the network of R43, C36, R53, and C39, is also input to U10, and controls the red LED current magnitude. Two NPN transistors (Q1 and Q2) act as current sources for the IR and red LED outputs. Two PNP transistors (Q3 and Q4) act as switches between the IR and red LED output lines. Transistor Q5 acts as an LED drive current limiter; it clamps output of the current regulator circuit to the required level. If any resistor in the LED drive circuit fails, current to the LED will still be limited to a safe level. The RSENS line senses the RCal value and enables the CPU to make the proper calculations based on the type of sensor being used.
Techni cal S upplement
coordinated with the LED transmission so that the IR and red signals are each sampled twice per cycle; that is, once when the LED is off (signal inverted), and once when the LED is on (signal not inverted). The filtering circuit that follows has a long time constant, thereby acting as an averaging circuit. A simplified N-20 HSO timing diagram is illustrated in Figure 9-10 (at the end of this section). If the instantaneous average photocurrent (DC offset) is excessive and U1D cannot bring it to VREF, the PHOTOI line to the CPU (HSI0) is activated. This action is an indication of excess ambient light into the photosensor, or the occurrence of excess noise in the input circuit. It also serves as a warning to the instrument that the sensor signal may be contaminated and causes the software to send an error message. After about 3 seconds of continuous photocurrent signal, pulse search annunciation will begin. After about 10 seconds of continuous photocurrent signal, zeros will be displayed. 9.9.7
Signal Gain
The separated IR and red signals are amplified so that their DC values are within the range of the A/D converter. Because the received IR and red signals are typically at different current levels, the signal gain circuits provide independent amplification for each signal as needed. The gain in these circuits is adjusted by means of the PWM lines. After the IR and red signals are amplified, they are filtered to improve the signal-to-noise ratio and clamped to a reference voltage to prevent the combined AC and DC signal from exceeding an acceptable input voltage from the A/D converter. 9.9.7.1 Variable Gain Circuits
Techni cal Supplement
The two variable gain circuits are functionally equivalent. The gain of each circuit is contingent upon the signals received level and is controlled to bring each signal to approximately 3.5 V. Each circuit uses an amplifier and one switch in the triple SPDT analog multiplexing unit U2. The gain in each of the circuits is accomplished by means of a feedback loop, which includes one of the SPDT switches in U2. The PWMs control whether the feedback loop is connected to ground or to the amplifier output. The feedback is then averaged by C33/R25 (red), and C34/R24 (IR). The higher the value of PWM2, the greater the IR gain; the higher the value of PWM1, the greater the red gain. 9.9.7.2 Filtering Circuits
The filtering circuits are illustrated in Figure 9-12. These circuits consist of two cascaded second-order filters with a break frequency of 10 Hz. Pairs of diodes (D1/D3 and D2/D4), that are located between VREF and ground at the positive inputs of the second amplifiers, maintain the voltage output within the range of the A/D converter. C13 REDDC
TP81 .12UF RED
R6 100K
C16
.12UF
11 15
R7 100K
U4D 16
14 OP490SO
R9 100K C14
C15 .068UF
R8
10 12
100K TP89
U4C
CR1
OP490SO VREF
Techni cal S upplement
otherwise be required to accurately compare the IR and red modulations between the combined AC and DC signals. The DC offsets are subtracted by using an analog switch to set the mean signal value to the mean of the range of the A/D converter whenever necessary. The AC modulation is then superimposed upon that DC level. This is also known as AC ranging. Each AC signal is subsequently amplified such that its peak-to-peak values span one-fifth of the range of the A/D converter. The amplified AC signals are then filtered to remove the residual effects of the PWM modulations and, finally, are input to the CPU. The combined AC and DC signals for both IR and red signals are separately input to the A/D converter. 9.9.8.1 Offset Subtraction Circuits
The AC variable gain control circuit is illustrated in Figure 9-13 (at the end of this section). Voltage dividers R22 and R41 (red), and R31 and R5 (IR), which are located between VREF and ground, establish a baseline voltage of 2.75 V at the input of the unity gain amplifiers U7C (red) and U7D (IR). Whenever SPST analog switches U11A and U11D are closed by HSO0 (active low), the DC portions of the IR and red signals create a charge, which is stored on C29 and C89, respectively. These capacitors hold this charge even after the switches are opened and the resulting voltage is subtracted from the combined signal— leaving only the AC modulation output. This AC signal is superimposed on the baseline voltage output by U7C and U7D. The IRDC and REDDC are then filtered and input to the CPU, and can be measured at TP58 and TP54, respectively. 9.9.8.2 AC Variable Gain Control Circuits
The AC variable gain control circuit is illustrated in Figure 9-13 (at the end of this section).
Techni cal Supplement
Measure Check Battery
Power supply & control
N-20/N-20P Control buttons
AUX PCB
Ambient light sensor
Main PCB AUX PCB
CPU
Display drivers
Main PCB Memory & software
Display
Audio beeper
AUX PCB (N-20 only)
Printer
To analog section Real-time clock
AUX PCB
Ambient temp. sensor
Main PCB
ON
ADV
D/D
Printer Control button
Figure 9-4: Digital Circuitry Block Diagram
9.10.1
CPU
A 16-bit microcontroller that includes a serial port, watchdog timer, A/D converter with an 8-input analog multiplexer, 3-pulse width modulators, and a high-speed I/O subsystem.
Techni cal S upplement
9.10.8
Thermal Printer (N-20P only)
Generates a hard copy of oxygen saturation and pulse rate values. A sensor monitors ambient temperature and adjusts printer output to ensure consistent print quality. 9.10.9
CPU
The CPU circuit is illustrated in Figure 9-14. The Intel 80C196KC CPU is a 16-bit microcontroller with built-in peripherals including: a serial port, watchdog timer, A/D converter with an 8-input analog multiplexer, three pulse width modulators, two 16-bit counter/timers, up to 48 I/O lines, and a high-speed I/O subsystem. The CPU is capable of running up to 16 MHz, but it is run at 10 MHz for decreased power consumption. All unused inputs are tied to either Vcc or ground through resistors—this prevents unused inputs floating to any voltage and causing excess power drain. The READY input pin is tied high, thereby disabling wait-state generation; all bus accesses are zero-wait state. The EA pin is tied low to enable addressing of the external EPROM. When the power supply is first switched on by the power control circuit, the reset generation circuit holds the CPU RESET pin low for at least 20 ms, then allows the internal pull-up resistor to bring it high; this assures a good CPU reset. An internal watchdog timer is enabled and runs continuously. The watchdog timer provides a means of recovering from a software upset caused by ESD, EMI, etc. If the software does not clear the timer at least every 64K state-times (13.1 ms), the CPU will drive RESET low, resetting the entire unit. The reset output by the CPU is only 16 state-times long (3.2 µs). Q22 provides isolation from C65 so the CPU can drive a good reset to the display control circuit.
Techni cal Supplement
Analog Reference Voltage
Ambient Light
Battery Voltage
Ambient Temperature Analog
Battery Power
Serial Interface
CPU Power Off
Control
Patient Sensor
SpO2 Analog Section
Analog Control
Address Decoding
AD Bus
Address Demultiplexing
s s e r d d A
AD Bus Enables
Output Port
Input Port
Power Control
CPU Memory
n O r e w o P
Power Control
Power Supply
Standard User Supply
Techni cal S upplement
The N-20 CPU is configured as follows: • • •
• • • • •
Decoded AD0 and BHE generate separate WR write strobes for the low and high bytes of a word. The signal WR (pin WRL) is the low-byte write strobe. A standard address latch enable (ALE) is generated and used. HSO pins 4 and 5 are configured as outputs. The HSO is used to generate stable timing control signals to the SpO2 analog section, display, and printer. The timer-2 external control pins T2CLK, T2RST, T2U-D, and T2CAPT are disabled via software and used as standard I/O. The HOLD, HLDA, and BREQ bus accessing is disabled via software and the pins are used as standard I/O. Pins HSI0 and EXTINT are configured for interrupt input. The CPU receives 2 external interrupts (signals PR_TACH and PHOTOI). RXD and TXD are configured as a standard asynchronous serial transmitter and receiver for the serial interface. PWM0, PWM1, and PWM2 pins are configured as pulse width modulator outputs. They are used to control gains within the SpO 2 analog section.
9.10.9.1 Address Demultiplexing
The address demultiplexing circuit is illustrated in Figure 9-15. U13 and U33 are transparent latches that latch the address portion of the AD bus data on the falling edge of ALE; the outputs are always enabled. The outputs of U13 and U33 are always the address portion of the AD bus.
Techni cal Supplement
9.10.9.2 Address Decoding
The address decoding circuit is illustrated in Figure 9-16. EXINEN EXOUTEN
TO: N-20
U28 WR RD
A10
A B C
6 4 5
G1 G2A G2B
Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
15 14 13 12 11 10 9 7
AUX PCB DC00-DFFF
74HC138
A12 A13 A14 A15
U30A 1 2 13
12
E000-FFFF RAMEN
74HC10
TP74
U30B A14 A15 A11
3 4 5
U30C 6
9 10 11
8
74HC10 TP71
20 20 HDR
ADDRESS DECODING 1 2 3
19
74HC10
0000-DBFF ROMEN
Techni cal S upplement
results. Due to the CPU configuration, the write strobe WR (WRL pin) is only active for low-byte writes; therefore, both bytes of the external output port must be written to at the same time. The upper byte of the output port cannot be written to alone, no write strobe and, therefore, no EXOUTEN signal will be generated. U30C generates the EPROMs active low enable signal, ROMEN. The active low signals RAMEN and EXINEN are basically used as EPROM disable signals. When RAMEN or EXINEN or test point TP71 are low, the output of U30C, ROMEN, is forced high, disabling the ROM. Therefore, the EPROM is disabled for the range DC00-FFFF and enabled for the 55 Kbyte address range of 0h-DBFF. TP71 is used during board testing to disable the EPROM. 9.10.10 CPU Memory
The CPU memory circuit is illustrated in Figure 9-17.
8K X 8 SRAM U14 A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12
10 9 8 7 6 5 4 3 25 24 21 23 2
A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12
D0 D1 D2 D3 D4 D5 D6 D7
11 12 13 15 16 17 18 19
VCC
AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7
Techni cal Supplement
U14 is a standard 8K ×8 static RAM. Test point TP 43 is used during testing to disable the output. The program that the CPU runs is stored in U15. U15 is a 16-bit wide output, one-time programmable (OTP) EPROM. During 16-bit wide bus accesses, the CPU uses address line A0 for low/high byte selection, and address line A0 is not used as a normal address line. The CPU can address only 64K ×8 bytes or 32K ×16 bytes. Pin A15 of U15 is tied low, always selecting the lower half of the EPROM. Signal ROMEN is then used to enable the EPROM for the proper memory area. 9.10.10.1
Input Port
The input port circuit is illustrated in Figure 9-18. EX_IN INPUT PORT U16 AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7
19 18 17 16 15 14 13 12
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
D1 D2 D3 D4 D5 D6 D7 D8 C OC
EXINEN
2 3 4 5 6 7 8 9 11 1
GO_BTN ON_OFF_BTN DD_BTN ADV_BTN PR_HOME BAT_TYPE RTC_IO
VCC
74HC573
Figure 9-18: Input Port Circuit
Techni cal S upplement
9.10.11 Real-Time Clock (RTC) and Non-Volatile Memory
The real-time clock circuit is illustrated in Figure 9-20. The RTC has two functions: (1) it provides non-volatile memory that is used to remember whether the printer should be enabled at power on, and (2) to keep track of time and date for the N-20P printer. The N-20 does not require or use the RTC; it is disabled via software.
REAL TIME CLOCK
VCC
CR22 1N914
TP86 TEST
U29 TP76
16 3 5 8
TEST CR23 C114 .1uF
1N914
R163 3.32K
BT1 3V
Y1
32.768KHz
VCC X1 X2 GND DS1202S
SCLK I/O RST
14 12
RTC_CLK RTC_IO
9
RTC_RST
TP85 TEST TP87 TEST
Techni cal Supplement
BEEP_1 BEEP_2
BZ1 TP74
TP75 TEST
TEST
AT17 BEEPER
Figure 9-21: Audio Output Circuit BZ1, a piezo ceramic sounder, is the audio output device. Due to its low drive current of 2 mA maximum, no drive circuitry is needed, and the audio output device is driven directly from the external output port. It is differentially driven with 2 square waves 180 degrees out of phase. The drive frequency is approximately 1480 Hz or 740 Hz and is generated by the CPU. BZ1 is differentially driven to obtain maximum audible volume. 9.10.13 Display Control Circuitry
The display control circuit is illustrated in Figure 9-22, at the end of this section. The Taliq display is controlled by the display control circuitry. A photosensor measures ambient light and automatically switches on the electroluminescent display backlight during low light conditions. The display control circuitry is divided into the following subsections: 9.10.13.1 Control Conditioning Circuit
Techni cal S upplement
9.10.13.4 Control Conditioning Circuit
The CPU generates a 400-µs low-pulse train at a 160 Hz rate on signal DISP_PHASE. Half of U34 takes DISP_PHASE as an input and creates DISP_POL as an 80 Hz 50% duty cycle square wave. A CPU reset initializes DISP_POL low when any CPU reset occurs so the software knows the initial state. The other half of U34 is used to synchronize the rising edge of the DISP_DL with the rising edge of DISP_POL. The CPU brings DISP_LATCH signal high before the rising edge of DISP_PHASE; this allows the high to be clocked out to DISP_DL on the rising edge of DISP_PHASE. About 100 µs after the rising edge of DISP_PHASE, the CPU brings DISP_LATCH low, asynchronously resetting DISP_DL low. 9.10.13.5 Display Driver Control Circuits
U19 and U20 are the display segment driver chips. Each chip has 32 high-voltage outputs and a display common marked BP (backplane). The display data are input to U19 and U20 by the CPU via a serial shift register input. U19 and U20 are daisy-chained together, forming a 64-bit s erial shift register. Display data are loaded and shifted down via the DISP_DATA and DISP_CLK signals. When all 64 bits of the shift register are loaded, a high pulse on DISP_DL updates the display, all 64 bits at the same time. The display is clocked with an 80 Hz 50% duty cycle waveform by signal DISP_POL. The display cannot be driven by DC voltages or display damage will result. Display segments are illuminated by creating a 180-degree phase shift between the segment pin and the BP common pin. Segments are left dark by making the waveform on the segment pin be in phase with the BP pin. The display has an electroluminescent (EL) backlight, and is driven the same as the display segments. Connectors JP2, JP3, and JP5 connect the display and EL backlight to the drive electronics.
Techni cal Supplement
VCC TP72 GO BTN R102 15K
TEST
To U21 pin 4
GO_BTN
TO: N-20 MAIN PCB
R78 150K
R79 3.32K
JP18 1
VCON
C66 .01UF
L11
GO_SW
2 C123
TP71 TEST
100PF
VCC
CHECK BATTERY
R71 150K TP88
R74
TEST
1K
SW1
L12
BAT_BTN
TP81 TEST
C126 100PF
C64 .01UF
Techni cal S upplement
• •
•
•
Batteries —Four 1.5-V alkaline "C" size batteries provide 4-6 VDC power. Power control circuitry —Power control circuitry is connected to the batteries. It senses any press of the Measure button and switches on the power supplies. Reverse current limiting protects the N-20/N-20P from damage if batteries are inserted incorrectly. Power shutoff circuit—This circuit controls power to all circuits except the power control circuit. In addition, a fuse protects the power supply from excessive current draw. The power supply is also protected against electrostatic discharge and electromagnetic interference. Power supply circuits consists of the following power supplies: Regulated power supply: Power supplied by the batteries is regulated at 5 VDC. All of the digital circuitry and some of the SpO2 analog circuitry use this supply. Unregulated power supplies: 5 VDC is converted by a switched capacitor network into unregulated power supplies of –5 VDC, 10 VDC, and 12 VDC, all of which are used in the SpO2 analog circuits. High voltage power supply: A voltage regulator/doubler converts battery power to 70 VDC; the display drivers as well as the display backlight need this increase in power.
The power supply circuit is illustrated in Figure 9-24, at the end of this section. 9.10.15.1 Power Control Circuitry
The power control circuit is illustrated in Figure 9-25, at the end of this section. The power control circuit consists of U21 and its associated components. U21 is a D flip/flop with asynchronous preset and clear; only the preset and clear are used.
Techni cal Supplement
Q15 part 1 controls the power supplies. When a logic high is placed on the gate (pin G1) signal, PWR_ON battery ground is connected to the circuit and switched to ground via Q15 parts 1 and 2. When the power control circuitry pulls PWR_ON low, switched ground switches to a high impedance state. This action switches off the power supply and, therefore the unit, except for the power control circuit. 9.10.15.3 Vcc Power Supply
Refer to Figure 9-24, "Power Supply Circuit,” at the end of this section. The Vcc power supply is a switched inductor voltage regulator operating in boost mode (U22). The power input is provided by the batteries (VBAT). NFET (Q17) operates as a linear post regulator. The 1 M resistor (R77) operates as a static bleed device across the switched regulator when the regulator is switched down. The regulated output is Vcc (5 V ± 5%). 9.10.15.4 Raw Power Supplies
Refer to Figure 9-24, "Power Supply Circuit,” at the end of this section. The input to the raw power supplies is Vcc, which is a switched-capacitor voltage converter operating in separate multiply and invert modes in conjunction with supporting circuitry. U23 inverts Vcc and outputs raw –5 V. Raw 10 V is derived by voltage doubling Vcc with CR14, CR19, CR20, and CR78. Raw 12 V is derived by voltage tripling Vcc with CR15, Q8, Q9, C96, C81, R119, and R120. The raw power supplies are used as bias supplies for the SpO2 analog section and are not tightly regulated. The normal operating range of the raw power supplies are:
Techni cal S upplement
VREF TP60 U32
R123
2 4
RAW10V 182
VIN GND
C95 22UF
VOUT TRIM
6 5
LT1021
R124 1
C12 22UF
C6 0.1UF
TP70 GND
R161 Q23 2N3904
10K
+5.7 VREF
Q24 2N3904
+12V R121 TP61
RAW12V 221
C91 22UF
C80 0.1UF
-5V R122 TP62
RAW-5V 221 C94 0.1UF
C93 22UF
Figure 9-26: Analog Reference Voltage Circuit
Techni cal Supplement
TEMP SENSOR U5 VCC
1
VCC 2
TEMP 3
PR_TEMP
GND
C115 0.1uF
LM35
Figure 9-28: Ambient Temperature Circuit U5 is a precision-temperature sensor. It outputs (PR_TEMP) a voltage proportional to the ambient temperature, which is 10 mV per degree centigrade. For example, at a room temperature of 25 °C, the U5 output would be 250 mV. U5 is used whenever an optional printer is installed. Because the printer is a thermal printer, ambient temperature must be compensated for. 9.10.19 Battery Voltage
The battery voltage circuit is illustrated in Figure 9-29. VBAT
BATTERY VOLTAGE SENSE
TP73
R69 15.8K 1% BAT_VOLT R70 47.5K 1%
C62 .01UF
Techni cal S upplement
the battery and the VRECHARGE terminals are mechanically connected. This applies the battery voltage to VRECHARGE, pulling BAT_TYPE high. R100 and CR27 are a current-limiting resistor and a voltage-clamping diode that are used to protect the input port from excessive battery voltage. If disposable batteries are used, VRECHARGE is electrically isolated, which allows R101 to pull BAT_TYPE input low. The nominal voltages and voltage discharge curves are significantly different between rechargeable and disposable batteries. In order for the CPU to predict how much "battery life" remains, the nominal voltage and discharge curves must be known; the BAT_TYPE signal provides that information. 9.10.21 Printer Control
Printer circuitry is divided into two subsections: the printer interface and the printer flex circuit. Printer interface circuitry is present on both models, but is disabled by software in the N-20. •
•
Printer interface circuit (auxiliary PCB)—This circuit detects the presence of the flex circuit, and supplies power to the print heads and paper-advance motor. Noise generated by the printer motor is filtered. The circuitry is protected from excessive battery currents by a fuse. The printer interface circuit is illustrated in Figure 9-31 (at the end of this section). Printer flex circuit (N-20P only)—The printer flex circuit is added when the printer is present. The printer generates a timing signal that is read by the CPU and sent to the flex circuit. This circuit signals the CPU that a printer is present by connecting one CPU input to ground. Power and power control signals from the auxiliary PCB generate an output load for a resistor array; heat from this process produces a dot matrix pattern on thermal paper. The printer flex circuit is illustrated in Figure 9-32.
Techni cal Supplement
SEIKO MTP102-16 PRINTER
TO N-20 AUX BOARD JP9
VPRN
JP10
TG
M+ MTG
HM
HM
1 2 3 4 5
HEADER 6 DOT4 U1
6 7 8 9 10 11 12 13
1 2 3 4 5 6
PR_DOT3
8 1 2 3 4 5 6 7
PR_DOT2
10
PR_DOT6 PR_DOT5 PR_DOT4
PR_DOT1
C3 PR_MOTOR
OUTM OUT0 OUT1 OUT2 OUT3 OUT4 OUT5 OUT6
VCC
GND
LB1256
PR_DOT0 3300UF
JP11
INM IN0 IN1 IN2 IN3 IN4 IN5 IN6
11 18 17 16 15 14 13 12 9
DOT6 DOT5 DOT4 DOT3 DOT2 DOT1 DOT0
8 7 6 5 4 3 2 1 HEADER 8
Techni cal S upplement
The N-20 is configured in two ways, with printer and without printer. The following is a description of the printer interface circuitry found on all N-20 auxiliary PCBs. The printer interface circuitry is there regardless of the unit configuration; however, if the optional printer is not installed, this circuitry serves no function. The CPU reads the PR_PRESENT signal to determine if a printer is installed. With PR_PRESENT left floating, it is pulled high by the weak pull-up resistor inside the CPU. If a printer is installed, PR_PRESENT is connected to switched ground, which causes a low input to the CPU. The optional printer circuit is protected from excessive battery currents by fuse F2. CR28 is used to block noise generated by the printer motor being injected onto the batteries. The N-20 printer is a 16-character–wide thermal dot matrix printer, which generates a CPU interrupt for every dot column. The thermal energy given to the print head is controlled by the pulse width of the active high signals PR_DOTx. In order to provide consistent print quality, the ambient temperature, print drive voltage, and print head resistance must be measured and accounted for. Inside the print head are seven resistors that heat up when power is applied, and in turn create dark dots on the thermal paper. One lead of the print-head resistors is connected to the printer supply voltage VPRN; the other lead is connected to the driver chip (see Optional Printer Flex Circuit with User Controls). One of the print dot resistor leads (DOT4) is also fed back to the printer interface circuitry. The DOT4 signal is a print dot resistor with a range of 11–16 ohms, which is connected to VPRN. The print head resistance is measured by U36. A two-level resistor bridge is formed by R143, R144, R145, R146, and head resistor DOT4. The resistor bridge is switched on when PR_MEAS is pulled high, pulling TP77 low and biasing the resistor bridge. The logic outputs of PR_HEAD1 and PR_HEAD2 are read in by the CPU to determine which of the three head resistance categories this
Techni cal Supplement
PWR_ON is high, the sources (S1, S2) short to the drains (D1, D2), connecting ground to U1 and C3. PWR_ON also controls the regulated power supplies; thus, Q1 and the power supplies are both enabled and disabled at the same time. The large bulk capacitor C3 is required due to the large current spikes that are required by the printer and the large internal series resistance of disposable batteries. Bulk capacitance is required to lessen the drop in battery voltage caused by the current spikes. The N-20P has three additional user-control buttons. L8, L9, L10, C120, C121, and C122 provide ESD protection. R103, R104, and R105 provide pull-ups when the user buttons are open. These pull-up resistors are in the printer interface circuit to ensure that the buttons (ON , ADV , and D/D) are never left floating, regardless of whether an optional printer flex circuit is installed or not. The optional user controls consist of three momentary push-button elastomeric contact switches. Pull-up resistors are provided by the printer interface circuitry. R1, R2, and R3 help protect the input port by providing some current-limiting capability. C4, C5, and C6 debounce the switch contacts.
9.11
Support Illustrations
These illustrations, at the end of this section, support the descriptions within this manual. Figure 9-8: LED Drive Circuit Figure 9-9: Differential Synchronous Demodulation Circuit Figure 9-10 N-20 HSO Timing Diagram
VCC
SENSOR INPUT
PWM1
LED DRIVE
C55
P1
TP45
4
R46 10K
.1UF
VREF 5 9 8 3 7 2 6 1
PWM2
Q3 MMBTA56
VCC
R45 Q4 MMBTA56
L3
13 2 1
L4 L5
R64 C116
C117
C118
100PF
100PF
100PF
5 3
10K
DB9F
Q1
TP46
TP47
MMBTA06
R48 10K
6 11 10 9
TP50 C119
X0
X
X1 Y Y0 Y1
Z
14 15 4
R135
6 U9A
R42
3.74K 1
4.7PF
280K
7 8
LT1013
TP83 2
R53
Z0 Z1 VSS INH A B
VEE
C
VDD
100K
8 7
C53
16
.1UF
C36
R43 20K
.1UF C39
4053
R51
VREF
C60
U10 12
10K
VCC
R50 182K
.022UF TP84
R52
100PF
TP48
22.1K
R54
100K
C37
6.8
.1UF
Q2
R18 6.04K
MMBTA06 RSENS
R44 20K
C38 R47 10K
Q5 2N3904
TO CENTER MTG. HOLE
TP77 .022UF
C5 .01UF
C123
22PF
PHOTOI IR/RED
IR/RED R49 100K R162 100K
CR12 OFF/ON 1N914 CR18 LED DIS 1N914 RSENS
Figure 9-8 LED Drive Circuit
TP78 R159
VREF
88.7K .1%
+12V
R63 2.0K
7
5
2 R160
U35 6
3
LT1097
51.1K R23
R158 88.7K .1%
SAMPRED SAMPIR OFF/ON
4 1 8
1M
-5V
8 6
7 U6D LTC201 U1D
12
VREF
14 13 LF444 C40
R2
390PF
1M
R17 3.32K
C1
1
TP49 3
18PF +12V R1
4
182K
3
U1A 9
R58 3.32K
11
R19 280K
RED
C24 .47UF
C59 .047UF VREF
2
U6C 10 LTC201
1 1 -5V
VREF
1 6
R157 511K C22 .047UF
14
15 U6B LTC201
R27
IR
3.32K C25 .47UF
TP44
SENSOR INPUT
82.5K
3.32K
1 LF444
VREF VREF
R57 40.2K
P1 5 9 4 8 3 7 2 6 1
R26
2 U6A LTC201
L1
U9B
R56
3 5
15.8K
4
PHOTOI
LT1013
TP79
DB9F
Figure 9-9 Differential Synchronous Demodulation Circuit
OFF/ON (HSO.1)
/SAMPIR (HSO.2)
/SAMPRED (HSO.0)
IR/RED (P1.1)
-60µS
-60µS
µS
0
105.6
State Time
0
66
158.4 177.6 99
111
283.2 177
336.0 337.2 210
211
443.2 277
496.0 515.2 310
322
620.8
673.6
388
421
Figure 9-10 N-20 HSO Timing Diagram
VCC
LTC201 5 U11B
LTC201 2 U11A 1
16
REDLED/AV
3
1 4
From U2 pin 3
IRLED/AV R20
REDDC
3.32K +5.7
R67
4 U7A
R29
1 2
REDAC
+
3.32K
LMC6044
C9 .015UF
TP54
.01UF
3.32K
3 RED
C7 .01UF
C61
C26 .1UF
C28 1NF
1 1
C27 .47UF
TP55
R30 100K
11 U11C LTC201
9
R28
10 R22
34.8K
VREF
12.1K
3.32K
2 1
U7C
10
5 3
8 9
R41 15K
6 11 10 9
R40 47.5K
LMC6044 TP85
C56 .01UF
U3 12 13
R60
X0 X1
X Y
Y0 Y1
Z
Z0 Z1
14 15 4
PWM1
TP56 VSS
INH A B C
VEE VDD
8 C58
7
.1UF
16
TP57
4053
VCC
R36
REDLED/AV PWM0
100K
IR
R21 C111 C29 .015UF
U7B
5
6 U11D LTC201
6
3.32K
LMC6044
+
C30
C31 .47UF
.1UF
7
C57 .01UF
C32 R31
C8 .01UF
R33
7 8
IRDC
3.32K
R66 3.32K
.01UF
VREF
TP58 IRAC
TP59
R61 3.32K
1NF
12.1K
/ZERO
R37 34.8K
13
TP76
U7D
BUS TO CPU
14 12 LMC6044
R5 15K
TP86
Figure 9-13 AC Variable Gain Control Circuit
EX_OUT LSB U18 AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7
2 3 4 5 6 7 8 9
EXOUTEN
11 1
R132 150K
D1 D2 D3 D4 D5 D6 D7 D8
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
19 18 17 16 15 14 13 12
DISP_DATA DISP_CLK RTC_CLK RTC_RST PR_MOTOR PR_MEAS BEEP_1 BEEP_2
CLK OC 74HC574
TP82 TEST EX_OUT MSB U17 AD8 AD9 AD10 AD11 AD12 AD13 AD14 AD15 EXOUTEN PR_STROBE R123
2 3 4 5 6 7 8 9 11 1
D1 D2 D3 D4 D5 D6 D7 D8
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
CLK OC 74HC574
19 18 17 16 15 14 13 12
PR_DOT6 PR_DOT5 PR_DOT4 PR_DOT3 PR_DOT2 PR_DOT1 PR_DOT0 RTC_IO
R148 R149
150K
VCC 150K
R150
150K
150K
R151
150K R152 150K
R153
R 15 4
1 50 K
150K
Figure 9-19 Output Port Circuit
DISP_POL
DISPLAYDRIVERS VCC
DISP_DL
U19 24 VDISP 28
VDD
VPP
TP80 TEST DISP_DATA
27
DISP_CLK
25 23 22 18 26
VCC
20 21
19
DIN CLK LATCH POL DOUT SL
OSCIN OSCOUT
GND
JP2 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24 O25 O26 O27 O28 O29 O30 O31 O32 BP
17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
+70V DISP_PHASE R93 182 1%
+70V TALIQ COLDSWITCH R113 4.75K
Q14 MMBT5401L VCC C87
R115
Q13 2N3904
475K
R117 6.19K
24
28
27 25 23 22 18
VCC
26
20 21
19
VDD
VPP
DIN CLK LATCH POL DOUT SL
OSCIN OSCOUT
GND
O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24 O25 O26 O27 O28 O29 O30 O31 O32 BP
17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30
390PF Q21 MMBT5551L
R114 12.1K
HDR32 R95 182 1%
JP3 U20
390PF C83
SI9530 VCC
VDISP
R116 10K Q12 MMBT5551L
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
DISPLAY PS CTRL U34
RST
10 12 11 13
HDR32
29
VCC
SI9530
4 2 3 1
14
SET1 D1 CLK1 RST1
Q1 Q1
SET2 D2 CLK2 RST2
Q2 Q2
VCC
GND
5 6
DISP_POL
9 8
DISP_DL
7
74HC74
EL DRIVE JP5 1 2 3 4 5 6 7 HDR7
Figure 9-22 Display Control Circuit
BATTERY INPUT BATTGND
TP3 TOCENTERMOUNTINGHOLE
TEST
BATTPLUS
R155 10K
TP1
F1
TEST
1.5A
POWER SUPPLY VBAT
R77 Q17
1M Q15 4 3 2 1
G2 S2
D2 D2
G1 S1
D1 D1
5 6 7 8
CR24 TRANZORB
C73 0.1UF
C116 22UF
C117 22UF
C74 22UF
R134 L1
150
U22 1 2
120UH
10V
3
SI9956DY
4 CR13
ILIM VIN
AO
SW2
GND
R82 100K
7
SET
SW1
2 3
8
FB
R84 10K
4
6
SRC SRC
8 7 6 5
DRN DRN DRN DRN
GATE
C76 100PF VCC
R85 100K
SI9405DY
C71 22UF
C72 .1UF
5
LT1173
130T3 C75 0.1UF
C70
C118
C119
22UF
22UF
22UF
R86 31.6K
R83 28.7K
RAW-5V
CR19
130T3
C78
CR20
+
U23 14 13 12 11 C82 22UF
R120
V+
FB/SD
OSC
CAP+
VREF
GND
VOUT
CAP-
3
.47UF
22.1K
RAW10V 130T3
C125 22UF
CR14 130T3
2N3906
4 5
Q9
C81
Q8
.1UF
CR15
C96 2.2UF
6
LT1054CS
R119
RAW12V 130T3
C79 22UF
2N3904
C90
TP38 TEST
22UF
C112
CR31
MURS110 +70V
U26 5 L2 120UH
6 7 8
1UF 50V
CR30 MURS110
VIN E1
FB
VSW
VC
E2
GND
CR16
3 2 1
3.32K C85
LT1172
MURS110
R96 CR25 5367A 43V10% 5W
C113 4.7UF 50V
C92 2.2UF 50V
C95 2.2UF 50V
R125 390K 1%
R126 390K 1%
C124 .1UF 100V
0.1UF R127 14K 1%
Figure 9-24 Power Supply Circuit
Q15
2 3
6
8
VCON
LT1046
CR11
TP84 VCC
VBAT
TEST TP72
R102 15K
TEST
1N914 C68 0.1UF
VCON
VCON U21
GO_BTN
TO: N-20 MAIN PCB
R79 3.32K
JP18 1
4 2 3 1
R78 150K
C66 .01UF
L11
10 12 11 13
VCON
GO_SW R110 475K
2 C123 3 100PF
4
TP71 TEST
Q1 Q1
SET2 D2 CLK2 RST2
Q2 Q2
5 6
PWR_ON
TP83 TEST
VCC
GND
9 8
GO BTN
7
R81 74HC74 3.32K
C110 C67 0.1UF
5
14
SET1 D1 CLK1 RST1
TP73 TEST
0.1UF JP9 PIN 17
6 7 8 9
PWR_DOWN
Figure 9-25 Power Control Circuit
ON BTN DD BTN ADV BTN PR_PRESENT VPRN
11
U36B 13
PR_HEAD1
R143 14.0K
12
LT1017CS
TP78 TEST VPRN R144 1.24K
R146 1 4
VPRN
R106 150K PR_TACH VCC
R145 60.4K TP77 TEST
6
Q20 2N3904
R142 150K Q19
TO PRINTER PCB TP35 TEST
TP36 TEST
TP37 TEST
JP9 VPRN
CR29
C127
TG
100pf
HM
1N914
2N3904
R118 150K
1 2 3 4
R141
PR_HOME PR_MEAS
TP79 TEST
4
LT1017CS
VCC
59 5
U36A 3
PR_HEAD2
DOT4
1K
R147
VPRN 3.32K
PR_DOT6
R156 1K
PR_DOT5 PR_DOT4 PR_DOT3 PR_DOT2 PR_DOT1 PR_DOT0 PR_MOTOR
5 6 7 8 9 10 11 12 13 14 15
TP24 TEST
TP27 TEST
TP23 TEST
TP30 TEST
TP26 TEST
TP29 TEST
TP25 TEST
VPRN
16
PWR_ON
17
TP28 TEST
18 PR_PRESENT
L8
R104 VCC 150K
R103
L9
150K
L10
VCC R105 VCC
ON_OFF
20
ADV
21
DD
22
150K
22 HDR TP31 TEST
CR28
F2
130T3
1A
19
VBAT
VPRN
C122
C121
C120
100PF
100PF
100PF
TP32 TEST
TP34 TEST TP33 TEST
C115 0.1UF
Figure 9-31 Printer Interface Circuit
SAMPIR SAMPRED PWM1 AC + DC
Input Signal Conditioning
Signal Gain
AC Ranging
/ZERO PWM0
RED
Zeroing r e t r e v n I
and Current to Voltage Conversion
Offset Subtraction
Variable Gain and Filter
REDAC PWM2
DMUX
CPU PWM0 IR
Sensor
Variable Gain and Filter
Variable Gain and Filter
Offset Subtraction
Variable Gain and Filter
IRAC
AC + DC RSENS /ZERO IR/RED
RED IR
LED Drive
OFF/ON LED DIS PWM0, PMW1, PWM2
Output
Figure 9-33 N-20 SpO2 Analog Block Diagram
CPU
VREF U31
REDDC REDAC IRDC IRAC RSENS AMB_LIGHT BAT_VOLT PR_TEMP PR_TACH
ALE RD WR AD15 AD14 AD13 AD12 AD11 AD10 AD9 AD8 AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0
13 12 6 5 7 4 11 10 8 9 15 14 VCC 37 62 61 40 41 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
VREF ANGND ACH0/P0.0 ACH1/P0.1 ACH2/P0.2 ACH3/P0.3 ACH4/P0.4 ACH5/P0.5 ACH6/P0.6 ACH7/P0.7 EXTINT/P2.2 GND VPP ALE/ADV RD WRL/WR WRH/BHE AD15/P4.7 AD14/P4.6 AD13/P4.5 AD12/P4.4 AD11/P4.3 AD10/P4.2 AD9/P4.1 AD8/P4.0 AD7/P3.7 AD6/P3.6 AD5/P3.5 AD4/P3.4 AD3/P3.3 AD2/P3.2 AD1/P3.1 AD0/P3.0
T2CLK/P2.3 T2RST/P2.4 P2.6/T2U-D P2.7/T2CAPT HSI0 HSI1 HSI2/HSO4 HSI3/HSO5 HSO0 HSO1 HSO2 HSO3 P2.5/PWM0 P1.7/HOLD P1.6/HLDA P1.5/BREQ P1.4/PWM2 P1.3/PWM1 P1.2 P1.1 P1.0
44 42 33 38 24 25 26 27 28 29 34 35 39 32 31 30 23 22 21 20 19
PR_HEAD1 PR_HEAD2 REDLED/AV /ZERO PHOTOI DISP_PHASE PR_STROBE SAMPRED OFF/ON SAMPIR PWM0 PR_PRESENT IRLED/AV PWR_DOWN PWM2 PWM1 DISP_LATCH IR/RED LEDDIS 10K
READY INST BUSWIDTH NMI CLKOUT RXD/P2.1 TXD/P2.0 EA RESET XTAL2 XTAL1
43 63 64 3 65 17 18 2 16 66 67
80C196KC
R131
RST
VCC
RAMEN NMI TP4
RXD TXD EA RST
R76 10K
C88
22PF C89
R137 10K
R75 10K
Y2 10MHz
22PF
RESET GENERATION VCC
VCC
R72 100K
TP41
C65 .1UF TP42
RST
R73 15K CR10 1N914
Q22 2N3904 R156 15K
Figure 9-34 CPU Circuit
LIGHT SENSOR TO: N-20
VCC
SpO2 ANALOG
DIGITAL SECTION
VCC D8 VTB8442B
AUX PCB R80
JP8 GO_SW
Q8 MMBTA13L
TP78
+12V
R159 VREF
88.7K .1%
+12V R63 2.0K
7
C125
.1UF TANT ACROSSU35 -5V SUPPLY
U35
3
R23
R158 88.7K .1%
1M
.1UF
C21 22UF TANT ACROSSU6 SUPPLY
-5V -5V
-5V
C35
7
.1UF
8
C1 18PF
TP49
R19 280K
4 U1A
11
R58 3.32K
3
L-8
DB9F
R26
2 U6A LTC201
Q6 C33 1NF
1 1
LF444
14
C24 .47UF
R46 10K
.1UF
VREF
R27
15 U6B LTC201
C1 18 100PF
100K
C14 TP89
MMBTA06
5 3 6 11 10 9
TP50
VREF
3 1 3
X0 X1
X Y
Y0 Y1
Z
Z0 Z1 VSS INH A VEE B C VDD
14 15
U9A
1
3.32K
LT1013
2
U4B
C111 .01UF C29 .015UF
C36 .1UF
C20
R43 20K
.1UF .022UF
8
VSS INH A VEE B C VDD
C58
7
.1UF
16
TP57
R5 15K
13
R123
2 4
RAW10V 182
C95 22UF
VIN GND
VOUT TRIM
6 5
LT1021
R124 1
C12 22UF
C6 .1UF
1N914
100K
1N914
TP70 GND
U7D
R57 40.2K
14
TP76
LMC6044 TP86
U9B
R56
2 3 4 5 6 7 8 9
3 5 4
PHOTOI
ALE
LT1013
11 1
TP39
10K Q24 2N3904
VREF
+5.7
C51
C52
.1UF
.1UF
.1UF
C48 22UF
C49 22UF
AD8 AD9 AD10 AD11 AD12 AD13 AD14 AD15 TP73
C102
C105
C1 06
C 10 7
C108
C109
.1UF
.1UF
.1UF
.1UF
.1UF
.1UF
R69 15.8K 1% BAT_VOLT
BATTERY VOLTAGE SENSE
R70 47.5K 1%
C62 .01UF
TP64 C91 22UF
C80 .1UF
TEMP SENSOR VCC
RAW-5V
1
VCC TEMP
TP62 221 C94 .1UF
C93 22UF
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
19 18 17 16 15 14 13 12
16
Q2 Q2
17
VCC
GND
18 19 20
7
20HDR
74HC74 RAMEN NMI TP4
RXD TXD EA
TP66 VCC RST
L6
TXD RXD
TP65
R128 10K
JP1
BEAD L7
R75 10K
1 2 3 4
BEAD
SERIAL DATA PORT
4HDR
C121
C120
100PF
100PF
AD15
A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12
74HC573 R108 10K
3
GND LM35
2 3 4 5 6 7 8 9 11 1
D1 D2 D3 D4 D5 D6 D7 D8
RAMEN
C OC 74HC573
19 18 17 16 15 14 13 12 TP5 TP6 TP7 TP8 TP9 TP10 TP11 TP12 TP13 TP14 TP15 TP16 TP17 TP18 TP19 TP20
2
PR_TEMP
A8 A9 A10 A11 A12 A13 A14 A15
10 9 8 7 6 5 4 3 25 24 21 23 2 20 26 27 22
WR RD Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
VCC
VCC
3 4
AD13
5
U14
A0 A1 A2 A3 A4 A5 A6 A7
C OC
TP21 TP22
U5 -5V R122
D1 D2 D3 D4 D5 D6 D7 D8
R109 10K
TP61
221
ALE TP40
+12V R121 RAW12V
SET2 D2 CLK2 RST2
8K X 8 SRAM
U33
RSENS
Q23 2N3904 C50
DISP_DL
15
2
AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7
VCC
C11 22UF
9 8
14
VCC
1
LEDDIS
TP63
DISP_POL
JP7
ADDRESS DEMUX
VBAT R161
14
VCC
5 6
13
VBAT
10 12 11 13 VCC
Q1 Q1
RESET GENERATION
OFF/ON CR18
RST
SET1 D1 CLK1 RST1
12
RAW-5V
TP59
22PF
R162
U34 4 2 3 1
Y2 10MHz
IR/RED
100K
11
RAW12V
22PF
IR/RED
TP60
TALIQ PS CTRL
IRAC
C31 .47UF
TP80
CR12
R137 10K
RAW10V
TP58
+
C30
TP79
R49
10
DISP_DL
PWM0 PR_PRESENT IRLED/AV PWR_DOWN PWM2 PWM1 DISP_LATCH IR/RED LEDDIS R131
9
DISP_POL
R76 10K
22PF C89
12
.022UF
VREF
7
DISP_PHASE
DISP_PHASE PR_STROBE SAMPRED OFF/ON SAMPIR
10K
IRDC
VREF R37
R44 20K
PR_HEAD1 PR_HEAD2 REDLED/AV /ZERO PHOTOI
43 63 64 3 65 17 18 2 16 66 67
READY INST BUSWIDTH NMI CLKOUT RXD/P2.1 TXD/P2.0 EA RESET XTAL2 XTAL1 C88
/ZERO
TOCENTERMTG.HOLE
U32
VPP ALE/ADV RD WRL/WR
REDLED/AV PWM0
C8 .01UF
44 42 33 38 24 25 26 27 28 29 34 35 39 32 31 30 23 22 21 20 19
T2CLK/P2.3 T2RST/P2.4 P2.6/T2U-D P2.7/T2CAPT HSI0 HSI1 HSI2/HSO4 HSI3/HSO5 HSO0 HSO1 HSO2 HSO3 P2.5/PWM0 P1.7/HOLD P1.6/HLDA P1.5/BREQ P1.4/PWM2 P1.3/PWM1 P1.2 P1.1 P1.0
VCC
1NF
15.8K C123
VREF ANGND ACH0/P0.0 ACH1/P0.1 ACH2/P0.2 ACH3/P0.3 ACH4/P0.4 ACH5/P0.5 ACH6/P0.6 ACH7/P0.7 EXTINT/P2.2 GND
R61 3.32K
TP77
C5 .01UF
13 12 6 5 7 4 11 10 8 9 15 14 VCC 37 62 61 40 41 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
AD14
TP84
C37 .1UF
6
PWR_DOWN
U13
C38 Q5 2N3904
TP56
.1UF C57 .01UF
VREF
34.8K
R47 10K
PWM1
1N914
R50 182K
100K
RSENS
4
Z
Z0 Z1
3.32K
LMC6044 C32
R31
AD15 AD14 AD13 AD12 AD11 AD10 AD9 AD8 AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0
15
Y
R33
7 6 U11D LTC201 7
CR4 12.1K
R52
MMBTA06
X
Y0 Y1
3.32K
R66 3.32K
U7B
5
6
1N914 TP90
C39
VCC
X0 X1
R21
8 .068UF
C53
16
6 11 10 9
R40 47.5K
CR2
TP83
R53
ALE
C56 .01UF
14
100K
VREF
100K
7
5 3
LMC6044
OP490SO R42 280K
7
8
2 1
5
8 4
U3 12 13
R36
4.7PF
TP55
RD
U7C
TP85
R12 100K
C60
6
C27 .47UF
4053
Q2
R18 6.04K 0.1%
R60
34.8K
-5V 6
REDAC
WR
R41 15K
C19 .12UF
OP490SO
100K C17 .068UF
C26 .1UF
8 1
R10
R28
12.1K
22.1K
R54 6.8
TP48
10
100K
OFF/ON
4053
R51
VREF
100PF
U11C LTC201
U4A
Q25 2N3906
REDDC REDAC IRDC IRAC RSENS AMB_LIGHT BAT_VOLT PR_TEMP PR_TACH
TP54
+
100K
11
9
1N914
R22
.12UF
7
U10 12 13
R48 10K
U31
.01UF
C28 1NF
1 1
5
8
CPU
VREF
R30
CR3 1N914
4
C7 .01UF
3.32K
LMC6044
C9 .015UF
OP490SO C R 1 V RE F
+12V
LF444 R135 3.57K
2
12
100K
4
PR_PRESENT
REDDC
R29
1 10
C18
2
VCC
Q1
TP46
C119
OP490SO
TP52 R11
VREF
10K
10K
TP47
100K
.068UF
U1B
5 C25 .47UF
2 1 C 117 100PF
6
82.5K
R64 C116 100PF
1NF
3.32K
L4 L5
R8
7
Q4 MMBTA56
L3
16 14
TP51
2N3906
R24
R45
Q3 MMBTA56
TP45
R9
C15 .068UF
C127 220PF VREF
Q7
LED DRIVE
C55
U4D
100K
10
VCC
L1 L2
U1C
9
U4C
11
R7
2N3906
82.5K
1 6
C22 .047UF
TP44
.12UF
3.32K
U7A
3 15
8
C34
VREF
100K
4
3.32K
C59 .047UF
R157 511K
C126 220PF VREF
3
TP53
3.32K C61
R67
+5.7
.12UF
R25
1
2 LF444
-5V
5 9 4 8 3 7 2 6 1
TP87
R20
C16
R6
VREF
INPUT
TP88
TP81
47.5K
13 12
X1 X0
1
10
REDLED/AV
3
C13
1 2
Y X
R39
2
PR_HEAD2
PR_TACH
IRLED/AV
3 5
Y1 Y0
4053
+12V R1 182K
P1
Z
14
R2
3
U6C LTC201
INH VSS
15
1M
9 10 11 6
C B A
VEE
14 LF444
SENSOR
VDD
4
C63 .01UF
PWM2 SAMPRED SAMPIR OFF/ON
Z1 Z0
U1D
GO BUTTON
PR_HEAD1
TP75
1
16 1 4
1
221 S2
PR_STROBE
LTC201 2 U11A
OFF/ON U2
VCC
13 C40 390PF R17 3.32K
LTC201 5 U11B
C23 22UF TANT ACROSSU11 SUPPLY
4 1 8
7 U6D LTC201
12
VREF
9
VREF
.1UF
8 6
R136 33.2K
VCC
C122
16
-5V
+12V
-5V
LT1097
51.1K
TP72
R68 2.2M
6
R160
+12V
C124
5
2
+12V
A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12
D0 D1 D2 D3 D4 D5 D6 D7
11 12 13 15 16 17 18 19
AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7
C65
R72 100K
TP41
AD12
6
AD11
7
.1UF AD10
TP42 RST
R73 475K
8
AD9
9
AD8 CR10 1N914
Q22 2N3904 VCC
10
AD7
R156 475K
11
AD6
12
AD5
CS1 CS2 WE OE
R133 10K
13
AD4
14
AD3
15
AD2
16
AD1
17
TP43 AD0 A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15
ROMEN RD
64K X 16 EPROM
18 EXINEN
U15
A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 ROMEN RD VCC VCC
24 25 26 27 28 29 30 31 32 35 36 37 38 39 40 41 3 22 2 43
A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 CE OE VPP PGM
O0 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15
21 20 19 18 17 16 15 14 11 10 9 8 7 6 5 4
AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 AD8 AD9 AD10 AD11 AD12 AD13 AD14 AD15
EXOUTEN
ADDRESS DECODING WR RD A10
A B C
6 4 5
20
TO: N-20
U28 1 2 3
19
20HDR
15 14 13 12 11 10 9 7
Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
G1 G2A G2B
AUX PCB DC00-DFFF
74HC138 A12 A13 A14 A15
U30A 1 2 13
12
E000-FFFF RAMEN
8
0000-DBFF ROMEN
27C1024L 74HC10
TP74
U30B C115 .1uF
A14 A15 A11
3 4 5
U30C 6
9 10 11
74HC10 74HC10
TP71
NOTES: 1. ALLRESISTORS1/8W 1%UNLESSOTHERWISESPECIFIED.
10K R134 VCC
Figure 9-35 Main PCB Schematic Diagram
BATTERY INPUT TP3 BATTGND
TOCENTERMOUNTINGHOLE TEST
R155 10K
TP1
POWER SUPPLY
VBAT
F1
R77
BATTPLUS
Q17 TEST
1.5A
1M Q15 4 3
VCC CR27 1N914 TP2
G2 S2
2 1
G1 S1
5 6
D2 D2
CR24 TRANZORB 10V
7 8
D1 D1
C116 22UF
C73 .1UF
C117 22UF
C74 22UF
U22
R134 L1
1
150
2
120UH
4
VRECHARGE TEST
2 3
8 R82 100K
7
SET
SW1
AO
SW2
GND
R84 10K
SRC SRC
4
8 7 6 5
DRN DRN DRN DRN
GATE
6
R85 100K
SI9405DY
VCC
C76 100PF
C71 22UF
C72 .1UF
5
LT1173
15K R101 150K
6
FB
VIN
3
SI9956DY
R100
ILIM
BAT_TYPE
VCON C75 .1UF
TP84
2
3
C70
C118
C119
22UF
22UF
22UF
R86 31.6K
R83 28.7K
TEST LT1046
RAW-5V
C68 .1UF
8 VCC TP72 R102 15K
C78 TEST
VCON
VCON
GO_BTN
4 2 3 1
R78 150K
MAIN PCB R79 3.32K JP18
VCON
C66 .01UF
L11
10 12 11 13
GO_SW
1
+
U21
TO: N-20
R110 475K
2 3 4
PR_HEAD1
C123
PR_HEAD2
100PF
TP71 TEST
PWR_ON
14 13 TP83 TEST
SET2 D2 CLK2 RST2 VCC
12
9 8
Q2 Q2
FB/SD
OSC
CAP+
VREF
11
22.1K 4 C81 5
C96 2.2UF
RAW12V
6
CAP-
.1UF
LT1054CS
C79 22UF
R119
C90
22.1K
TP38 TEST
C112 1UF 50V
22UF JP9 PIN17
.1UF
TP73 TEST
+70V U26
PR_TACH
6
5 PR_PRESENT
7
L2 120UH
8
E1
7
VSW
8
E2
DISP_PHASE DISP_POL
11
TALIQDRIVERS
DISP_DL
12
U19 24
13
RAW10V
14
RAW12V
15
RAW-5V
16
VCC
VDISP 28
VPP
TEST
17 18
VDD
TP80
VBAT
DISP_DATA
27
DISP_CLK
25 23
19
22
20 20HDR
18 26
VCC
JP17
DIN CLK LATCH POL DOUT SL
1 2 3 4
AD15
20
AD14
21
OSCIN OSCOUT
AD13
5
AD12
6
19
AD11
7
GND
BP
17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29
AD8
24
VDD
AD7
11
28 AD6
12
VPP
AD5
13
AD4
14
27 AD3
15
25 AD2
16
23 AD1
17
22 AD0
18
18 EXINEN
19
VCC
EXOUTEN
20
26
DIN CLK LATCH POL DOUT SL
20HDR
TO: N-20
20 21
MAIN PCB
19
OSCIN OSCOUT
GND
C85 .1UF
R71 150K
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
TP88
R74
TEST
1K
O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24 O25 O26 O27 O28 O29 O30 O31 O32 BP
17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30
C100
C101
.1UF
.1UF
C49 22UF
1 2 3 4 5 6 7
C87 390PF
VDISP
VPRN U36B
U16 AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7
19 18 17 16 15 14 13 12
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
2 3 4 5 6 7 8 9
D1 D2 D3 D4 D5 D6 D7 D8 C OC
11 1
GO_BTN
PR_HEAD1
11
R143 14.0K
13
R115
LT1017CS R144 1.24K
R146 1 4 PR_HEAD2
59
VPRN R106 150K
PR_TACH
EXOUTEN
11 1
D1 D2 D3 D4 D5 D6 D7 D8
19 18 17 16 15 14 13 12
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
DISP_DATA DISP_CLK RTC_CLK RTC_RST PR_MOTOR PR_MEAS BEEP_1 BEEP_2
VCC
R118 150K
TP77 TEST
R142
TOPRINTERPCB Q20 2N3904
150K
TP35 TEST
TP36 TEST
TP37 TEST
JP9
Q19
VPRN
C127
TG
100pf
HM
2N3904
DOT4
1K
R147
VPRN 3.32K
R156
PR_DOT6
1K
74HC574
BZ1
PR_DOT5 TP74
TP82 TEST
PR_DOT4 TP75 TEST
EX_OUTMSB U17 AD8 AD9 AD10 AD11 AD12 AD13 AD14 AD15 EXOUTEN PR_STROBE
2 3 4 5 6 7 8 9
D1 D2 D3 D4 D5 D6 D7 D8
11 1
TEST
PR_DOT3
AT17 BEEPER
PR_DOT2
PR_DOT6 PR_DOT5 PR_DOT4 PR_DOT3 PR_DOT2 PR_DOT1 PR_DOT0 RTC_IO
PR_DOT1 PR_DOT0 PR_MOTOR
TP24 TEST
R148
74HC574
150K
REAL TIME CLOCK
U29
TP76 TEST
16 3 5 8
CR23 C114 1N914 .1uF
R163
Y1
VCC X1 X2 GND
SCLK I/O
DS1202S
RST
14 12
RTC_CLK RTC_IO
9
RTC_RST
2 3
5 6 7 8 9 10 11 12 13 14 15
CLK OC
R123 VCC
19 18 17 16 15 14 13 12
Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
1
4
PR_HOME
CLK OC
R132 150K
R95 182 1%
R145 60.4K
6
R141
PR_MEAS
Q21 MMBT5551L
3 4
U18 2 3 4 5 6 7 8 9
R117 6.19K
R114 12.1K TP79 TEST
5
LT1017CS VCC
AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7
C83 390PF Q13 2N3904
475K
VPRN
U36A VCC
R116 10K
Q12 MMBT5551L
TP78 TEST
12 ON_OFF_BTN DD_BTN ADV_BTN PR_HOME BAT_TYPE RTC_IO
74HC573
EXINEN
VCC
JP5 VCC
C99 .1UF
Q14 MMBT5401L
VCC
PR_PRESENT
EX_ININPUTPORT
150K
R149
R150
150K
150K
R151
R152
150K
150K
R153
R154
TP23 TEST
TEST TP87 TEST
TP26 TEST
TP30 TEST TP29 TEST
VPRN
16
PWR_ON
17
TP28 TEST
18 PR_PRESENT
VCC
VCC
L8
R104 150K VCC R105
ON_OFF ADV
21
L10
150K
19 20
L9
R103
DD
22
150K
150K
22HDR TP31 TEST
TP85
TP27 TEST
TP25 TEST
150K
C98
R93 182 1% TALIQCOLDSWITCH R113 4.75K
29
ELDRIVE
+70V
+70V
C64 .01UF
100PF
SW1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
DIGITALIC'SBYPASSCAPS
R127 14K 1%
TEST
HDR32
HDR32
C124 .1UF 100V
TP81
TEST
.1UF
R126 390K 1%
BAT_BTN C126
TP86
C97
C95 2.2UF 50V
C113 4.7UF 50V
DISP_PHASE
L12
SI9530
.1UF
CR25 5367A 43V10% 5W
3.32K
1
EX_OUTLSB
VCC U20
10
R96
2
LT1172
JP3 AD9
9
VC GND
3
JP2 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24 O25 O26 O27 O28 O29 O30 O31 O32
SI9530
AD10
8
VCC
CHECK BATTERY
VCC
FB
R125 390K 1%
C92 2.2UF 50V
CR30 MURS110
VIN
6
PWR_DOWN
9 10
C125 22UF
3
GND
VOUT
C82 22UF
7
GND
V+
C110 C67 .1UF
RAW10V
R120 .47UF
5 6
Q1 Q1
74HC74 3.32K
PR_STROBE
5
14
R81
U23
SET1 D1 CLK1 RST1
F2 VBAT
VPRN
C122
C121
C120
100PF
100PF
100PF
TP32 TEST
TP34 TEST TP33 TEST
1A C115 .1UF
32.768KHz
3.32K
HDR7
BT1 3V
Figure 9-36 Auxiliary PCB Schematic Diagram