Novametrix Medical Systems 7300 User manual

Novametrix Medical Systems Inc.
P.O. Box 690
5 Technology Drive
Wallingford, Connecticut, U.S.A. 06492.
Model 7300
Service Manual
Aug 27, 1999
Part Number 9226-90-00

Rev. 00 Model 7300 Service Manual iii
Service Policy Novametrix Medical Systems Inc. provides 24-hour a day access to technical support
through its Technical Support Department in Wallingford, Connecticut, and company
Service Representatives located throughout the United States. (Outside the U.S.,
primary technical support is handled through our qualified international sales and
service distributors.)
Novametrix will provide Warranty Service support within 48 hours of receiving a request
for assistance. Contact the Technical Support Department by telephone toll free at 800-
243-3444, or 203-265-7701; by facsimile at 203-284-0753; or, by e-mail at
[e-mail]. After hours telephone support requests (before 8:00 AM
and after 5:00 PM Eastern Time) will be responded to promptly by the Technical
Support on-call staff. After hours facsimile and e-mail requests will be answered the
next business day. It is suggested that any person calling in for technical support have
the equipment available for product identification and preliminary troubleshooting.
Novametrix reserves the right to repair or replace any product found to be defective
during the warranty period. Repair may be provided in the form of replacement
exchange parts or accessories, on-site technical repair assistance or complete system
exchanges. Repairs provided due to product abuse or misuse will be considered “non-
warranty” and invoiced at the prevailing service rate. Replaced or exchanged materials
are expected to be returned to Novametrix within 10 days in order to avoid (additional)
charges. Return materials should be cleaned as necessary and sent directly to
Novametrix using the return paperwork and shipping label(s) provided (Transferring
return materials to a local sales or dealer representatives does not absolve you of your
return responsibility.).
Novametrix manufactures equipment that is generally field serviceable. When repair
parts are provided, the recipient can call Technical Support for parts replacement
assistance and repair assurance. In the event a replacement part requires increased
technical capability, Technical Support may request Biomedical assistance, provide on-
site technical support or complete replacement equipment. If the customer requires the
return of their original product, the exchange material will be considered “loaner
material” and exchanged again after the customer equipment is repaired.
Novametrix promotes customer participation in warranty repairs, should they become
necessary. A longer useful product life, and quicker, more cost-effective maintenance
and repair cycles—both during and after the warranty period, are benefits of a smooth
transition into self-maintenance. The Technical Support Department can provide
technical product support at a level appropriate to your protocol and budget
requirements.
Please contact Technical Support for information on these additional programs and
services:
• Focus Series Technical Training Seminars
• Test Equipment and Test Kits
• Service Contract / Parts Insurance Plans
• On-Site Technical Support
• “Demand Services” including:
Flat rate parts exchange
Flat rate return for repair
Time and material,
Full warranty, discounted replacement sensors.

iv Model 7300 Service Manual Rev. 00
Warranty Equipment manufactured or distributed by Novametrix Medical Systems Inc., is fully
guaranteed, covering materials and workmanship, for a period of one year from the
date of shipment, except for certain disposable products and products with stated
guarantees other than one year. Novametrix reserves the right to perform guarantee
service(s) at its factory, at an authorized repair station, or at the customer’s installation.
Novametrix’ obligations under this guarantee are limited to repairs, or at Novametrix’
option, replacement of any defective parts of our equipment, except fuses, batteries,
and calibration gasses, without charge, if said defects occur during normal service.
Claims for damages during shipment must be filed promptly with the transportation
company. All correspondence concerning the equipment must specify both the model
name and number, and the serial number as it appears on the equipment.
Improper use, mishandling, tampering with, or operation of the equipment without
following specific operating instructions will void this guarantee and release Novametrix
from any further guarantee obligations.
Caution: Federal (U.S.A.) law restricts this device to sale, distribution, or use by or on
the order of a licensed medical practitioner.
Copyright ©1999. Novametrix Medical Systems Inc.,
5 Technology Drive, Wallingford, Connecticut, 06492.
All rights reserved.
Service Department
For factory repair service:
Call toll free: 1-800-243-3444
To Call Direct: [phone]
Facsimile [phone]
http://www.novametrix.com
[e-mail]

Rev. 00 Model 7300 Service Manual v
Table of Contents
Safety .............................................................................................................................................................. 1
Warnings .................................................................................................................................................. 1
Cautions ................................................................................................................................................... 2
Notes ........................................................................................................................................................ 2
Introduction .................................................................................................................................................... 5
About this manual ..................................................................................................................................... 5
Front and Rear Illustrations ...................................................................................................................... 5
NICO Monitor Technical Description ........................................................................................................ 6
Manufacturing Quality & Safety ................................................................................................................ 6
Declaration of Conformity with European Union Directive ........................................................................6
Trademarks and Patents .......................................................................................................................... 6
Manual Revision History ........................................................................................................................... 6
Theory of Operation ...................................................................................................................................... 7
NICO Model 7300 Non-Invasive Cardiac Output Monitor ......................................................................... 7
Digital Board 2763 .................................................................................................................................... 7
Microprocessor ..................................................................................................................................7
Background Mode Debugging and Application Development .........................................................11
System Memory .............................................................................................................................. 11
User Interface Control Circuitry ....................................................................................................... 12
Real Time Clock, Power on RESET Generation and Glue Logic ....................................................12
Power Supply 2764 (Power Supply and Communications) ....................................................................13
Serial Communications UART ......................................................................................................... 13
CO2Pulser Source Drive ................................................................................................................15
CAPNOSTAT Case and Detector Heater Control ........................................................................... 16
Saturation LED Power Generation and LED Drive .......................................................................... 17
Power Supply and Voltage Reference Generation ..........................................................................17
Logic and Input / Output Signal Control .......................................................................................... 20
Analog Board 2765-01 ............................................................................................................................ 20
CAPNOSTAT Interface ................................................................................................................... 20
CO2Input Signal Path ..................................................................................................................... 20
CO2Case and Detector Heater Regulation ....................................................................................21
Flow Zeroing and Patient Line Purging ........................................................................................... 22
Flow Circuitry ................................................................................................................................... 22
Barometric and Airway Pressure ..................................................................................................... 23
Patient Airway Adapter Type Sensing ............................................................................................. 23
NICO Sensor Rebreathing Valve Control ........................................................................................ 24
Saturation Input Signal Path and Signal Conversion ......................................................................24
Functional Testing ....................................................................................................................................... 25
Equipment Required ............................................................................................................................... 25
Functional Test ....................................................................................................................................... 25
Accuracy Tests ............................................................................................................................................ 29
Equipment Required ............................................................................................................................... 29
CO2 Testing ............................................................................................................................................ 29
SpO2Testing .......................................................................................................................................... 30
Flow Testing ........................................................................................................................................... 31
Time / Date Setting .................................................................................................................................31
Electronic Tests ........................................................................................................................................... 33

vi Model 7300 Service Manual Rev. 00
Equipment Required ............................................................................................................................... 33
Power Supply ......................................................................................................................................... 34
Voltage Checks ...................................................................................................................................... 35
CO2Testing ............................................................................................................................................ 37
SpO2Testing .......................................................................................................................................... 37
Flow, Barometric Pressure and Rebreathe Valve Testing ...................................................................... 38
Serial / Analog Testing ........................................................................................................................... 40
Safety Testing ........................................................................................................................................ 40
Maintenance ................................................................................................................................................. 41
General .................................................................................................................................................. 41
Maintenance Schedules ......................................................................................................................... 41
Cleaning and Sterilization ....................................................................................................................... 41
Monitor ............................................................................................................................................ 41
SpO2Finger Sensor ........................................................................................................................ 41
SpO2Y-Sensor .............................................................................................................................. 42
SpO2Y-Strip Tapes and Foam Wraps ........................................................................................... 42
Ear Clip ........................................................................................................................................... 42
NICO Sensors ................................................................................................................................. 42
CAPNOSTAT CO2Sensor .............................................................................................................. 42
Disassembly ........................................................................................................................................... 43
Equipment Required ....................................................................................................................... 43
Disassembling Unit ......................................................................................................................... 43
Reassembling Unit ................................................................................................................................. 44
Battery Maintenance .............................................................................................................................. 44
Replacing the Internal Battery ................................................................................................................ 44
Mains Voltage Configuration .................................................................................................................. 45
Fuse Replacement .......................................................................................................................... 46
Software Update Instructions ................................................................................................................. 47
Equipment Required ....................................................................................................................... 47
Setup ............................................................................................................................................... 47
Procedure ........................................................................................................................................ 48
Specifications .............................................................................................................................................. 51
General ................................................................................................................................................... 51
NICO ...................................................................................................................................................... 51
CO2 ................................................................................................................................................................................................ 51
Flow Sensor ........................................................................................................................................... 52
SpO2 .............................................................................................................................................................................................. 52
Monitor Specifications ............................................................................................................................ 52
NICO Accessories ....................................................................................................................................... 53
Parts Lists .................................................................................................................................................... 55
9226-00 Non-Invasive Cardiac Output Monitor, Model 7300 ................................................................. 55
9226-01 Main Assy ................................................................................................................................. 55
2763-01 Digital Board Assy .................................................................................................................... 56
2764-01 Power Board Assy .................................................................................................................... 58
2765-01 Analog Board Assy ................................................................................................................... 62
2766-01 CO2Input Board Assy ..............................................................................................................65
9392-01 Pump W Rsvr Assy .................................................................................................................. 65
Drawings ...................................................................................................................................................... 67

Rev 00 Model 7300 Service Manual 1
1Safety
For maximum patient and operator safety, observe the following warnings, cautions
and notes.
1.1 Warnings
• Explosion Hazard: Do not use the NICO monitor in the presence of flammable
anesthetics. Use of this instrument in such an environment may present an
explosion hazard.
• Electrical Shock Hazard: Always turn the NICO monitor off before cleaning it. Do
not use with a damaged external power source. Refer servicing to qualified
service personnel.
• Connect the AC Mains power cord to a properly grounded hospital-grade outlet.
The NICO monitor should be connected to the same electrical circuit as other
equipment in use on the patient. Outlets of the same circuit can be identified by
members of the hospital’s engineering department.
• Failure of Operation: If the monitor fails to respond as described, do not use it
until the situation has been corrected by qualified personnel.
• Reuse (disassembly, cleaning, disinfecting, resterilizing, etc.) of the NICO
sensor may compromise the device functionality and system performance and
cause a potential patient hazard. Performance is not guaranteed if the NCIO
sensor is reused.
• Inspect the CO2, SpO2and NICO sensors prior to use. Do not use if they appear
to be damaged or broken.
• Do not attempt to rotate the NICO sensor in the breathing circuit by grasping the
pneumatic tubes exiting the flow sensor.
• Do not apply excessive tension to any cable or the NICO sensor pneumatic
tubing.
• Periodically inspect NICO sensor tubing lines for kinks.
• Replace the NICO sensor if excessive moisture or secretions are observed in the
tubing.
• Do not use the NICO monitor if it is unable to properly identify the NICO sensor.
If the condition persists, refer the monitor to qualified service personnel.
• The NICO sensor connector should be properly inserted into the front panel
receptacle prior to connecting the NICO sensor to the breathing circuit, in order
to avoid a circuit leak, or occlusion of the NICO sensor tubing.
WARNING:
Indicates a potentially harmful condition that can lead to personal injury.
!

1 Safety Cautions
2Model 7300 Service Manual Rev. 00
• In the event the message NICO SENSOR FAILURE is displayed, remove the NICO
Sensor from the patient circuit.
• Patient Safety: Care should be exercised to assure continued peripheral
perfusion distal to the SpO2sensor site after application.
• Inspect the SpO2sensor site for adequate circulation at least once every four
hours.
• When applying sensors take note of patient’s physiological condition. For
example, burn patients may exhibit more sensitivity to heat and pressure and
therefore additional consideration such as more frequent site checks may be
appropriate.
• Do not position sensor cables or tubing in any manner that may cause
entanglement or strangulation.
• The NICO monitor is not intended to be used as a primary apnea monitor.
1.2 Cautions
• Use only Novametrix approved sensors and accessories with the NICO monitor.
• Do not operate the NICO monitor when it is wet due to spills or condensation.
• Do not operate the product if it appears to have been dropped or damaged.
• Never sterilize or immerse the monitor in liquids.
• Do not sterilize or immerse sensors except as directed in this manual.
• No tension should be applied to any sensor cable or tubing.
• To avoid the effects of excessive moisture in the NICO sensor, insert it in the
ventilator circuit with the pneumatic tubes upright. Excessive moisture in the
NICO sensor may affect the accuracy of the measurements.
• Operate the monitor at temperatures between 10 to +40° C (50 to 104° F),
10-95% R.H. non-condensing.
• Avoid storing the monitor at temperatures less than -10qC or greater than +55q
C (<14qF or >131qF) 10-95% R.H. non-condensing
• Observe precautions for electrostatic discharge (ESD) and electromagnetic
interference (EMI) to and from other equipment.
• Where electromagnetic devices (i.e., electrocautery) are used, patient
monitoring may be interrupted due to electromagnetic interference.
Electromagnetic fields up to 3 V/m will not adversely affect system performance.
• Caution: Federal (U.S.A.) law restricts this device to sale, distribution, or use by
or on the order of a licensed medical practitioner.
1.3 Notes
• In order to ensure proper monitoring of oxygenation and ventilation:
• The use of pulse oximetry is recommended during NICO monitoring.
• Setting of ETCO2and SpO2alert limits is recommended.
CAUTION:
Indicates a condition that may lead to equipment damage or malfunction.
NOTE:
A point of particular interest or emphasis intended to provide more efficient or convenient
operation.
!

Notes Safety 1
Rev. 00 Model 7300 Service Manual 3
• A “NO RESPIRATION” alert is not generated when both the CAPNOSTAT CO2
sensor and the NICO sensor are disconnected from the NICO monitor.
• Be certain that the monitor is not in Demo Mode while monitoring. Demo Mode
can be identified by the flashing DEMO MODE label in the General Message
area of the display. To exit Demo Mode and return to normal monitoring mode,
turn the power off and back on.
• The NICO monitor contains no user serviceable parts. Refer servicing to
qualified service personnel.
• Do not attach an SpO2sensor distal to a blood pressure cuff. Valid data cannot
be processed when the cuff is inflated. Attach the sensor to the limb opposite to
the site used for the blood pressure cuff.
• This product and its accessories which have patient contact are free of latex.
• The NICO monitor is Year 2000 compliant.
• Data Validity: Inaccurate SpO2and Pulse Rate values may be caused by;
• Incorrect application or use of a sensor
• Significant levels of dysfunctional hemoglobin; carboxyhemoglobin or
methemoglobin
• Significant levels of indocyanine green, methylene blue, or other intravascular
dyes
• Exposure to excessive illumination such as surgical lamps—especially ones
with a xenon light source, or direct sunlight
• Excessive patient movement
• Venous pulsations
• Electrosurgical interference
• Use of an IABP.
• NICO measurements will occur provided the following conditions are met:
• The NICO sensor is properly installed in the patient’s breathing circuit.
• Valid flow and CO2signals are detected with no significant signal artifact.
•VCO
2is greater than 20 mL/min.
•ETCO
2is between 15 and 70 mmHg (2.0 - 9.0 kPa or %)
• The tidal volume is greater than 200ml.
• The respiratory rate is between 3 and 60 br/min.
• The STOP/CONTINUE REBREATHING key is not illuminated.
• NICO is not paused by the monitor for any other reason (displayed in the C.O.
message area)
• When a new CAPNOSTAT CO2sensor is attached to the monitor, or is moved
from one monitor to another, it must be adapter zeroed before use.
• After the life cycle of the equipment and accessories has been met, disposal
should be accomplished following national/local requirements.
• There is no screen indication during monitoring, except on start-up (or when the
SET ALERTS screen is displayed), as to when the NICO alert settings are off.

1 Safety Notes
4Model 7300 Service Manual Rev. 00
[This page intentionally blank.]

Rev 00 Model 7300 Service Manual 5
2Introduction
2.1 About this manual
This document contains information which is proprietary and the property of
Novametrix Medical Systems Inc., and may not be reproduced, stored in a retrieval
system, translated, transcribed, or transmitted, in any form, or by any means, without
the prior explicit written permission of Novametrix Medical Systems Inc. Novametrix
reserves the right to change specifications without notice.
2.2 Front and Rear Illustrations
Front panel keys
Knob
Operate/standby key
CAPNOSTAT CO2sensor input connection
SpO2sensor input connection
NICO sensor input connection
Display screen
Power cord entry module
Rear panel power switch
Power cord retainer
Serial number label
Rear panel
power connectors
Equipotential connection
(connection to monitor chassis)
(power cord receptacle
and fuse housing)
(secure power cord)

2 Introduction NICO Monitor Technical Description
6Model 7300 Service Manual Rev. 00
2.3 NICO Monitor Technical Description
Per requirements of IEC 601-1, the NICO monitor is classified as class II equipment,
internally powered, with type BF applied part, and an enclosure protection rating of
IPX0. The NICO monitor is Year 2000 compliant.
Transport/Storage: -10 to +55° C (14-131° F), 10-95% R.H. non-condensing
Operating Conditions: 10 to +40° C (50 to 104° F), 10-90% R.H. non-condensing
2.4 Manufacturing Quality & Safety
The Novametrix Medical Systems Inc. manufacturing facility is certified to both
ISO 9001 and EN46001 (MDD93/42/EEC Annex II). Novametrix’ products bear the
“CE 0086” mark. The product is certified by Underwriter’s Laboratories (UL) to bear the
UL mark; and tested by TÜV Rheinland to IEC 601-1/EN60601-1.
2.5 Declaration of Conformity with European Union Directive
The Authorized Representative for Novametrix equipment is:
D.R.M. Green
European Compliance Services Limited,
Oakdene House,
Oak Road,
Watchfield
Swindon, Wilts SN6 8TD
United Kingdom
2.6 Trademarks and Patents
CAPNOSTAT CO2Sensor is a registered trademark (®) and NICO, NICO2and the
stylized NICO2with CO2 shadow, NICO Sensor, NICO Loop and CObar (cardiac
output confidence bar), SuperBright and Y-Sensor are trademarks (™) of Novametrix
Medical Systems Inc. Other trademarks and registered trademarks are the property of
their respective owners.
NICO and its sensors and accessories are covered by one or more of the following USA
patents: 4,859,858, 4,859,859, 4,914,720, 5,146,092, 5,153,436, 5,190,038,
5,206,511, 5,251,121, 5,347,843, 5,369,277, 5,379,650, 5,398,680, 5,616,923,
5,693,944, 5,789,660. Other patents pending.
2.7 Manual Revision History
7-Aug-99 Release

Rev 00 Model 7300 Service Manual 7
3Theory of Operation
3.1 NICO Model 7300 Non-Invasive Cardiac Output Monitor
The NICO model 7300 monitor measures cardiac output based on changes in
respiratory CO2concentration caused by a brief period of rebreathing. The
measurement of cardiac output is accomplished by interpreting data collected by
proprietary sensors that measure flow, airway pressure, and CO2concentration, and
then combining these signals to calculate CO2elimination. Using these variables, a
technique known as Fick partial rebreathing is applied to calculate cardiac output.
NICO can be used with mechanically ventilated patients in the operating room,
intensive care, or emergency departments.
3.2 Digital Board 2763
3.2.1 Microprocessor
Refer to sheet 1 of the 2763-03 schematic.
The generation of the logic and control signals for the purpose of acquiring the raw
physiological parameters, and management of the data needed to produce an accurate
Non-Invasive Cardiac Output, are the responsibilities of microprocessor IC1. This
device, a Motorola MC68332, is a highly integrated 32-bit microcontroller that
combines high-performance data manipulation capabilities with powerful peripheral
subsystems. These subsystems include circuitry for timing generation, peripheral chip
selection and data control, interrupt generation, as well as synchronous and
asynchronous serial communication. Also included is a sophisticated timing co-
processor, the TPU (Time Processor Unit), that can generate complex timing
waveforms independent of the main processor. In general, the signals for subsystems
are functionally grouped into ports which can be independently programmed by
software to be a pre-defined port function or discrete I/O. Additionally, the functionality
for several ports (Ports C, E and F) can be pre-defined by the state of specific data bus
lines on system power-up. Included is a special “background mode” port that allows the
device to be externally controlled, facilitating system debugging and testing. Also
integrated on-chip are several activity monitors as well as a software watchdog to
ensure proper device and system operation. Refer to table 1.
Port Defined Function Functionality & Power-up Control
TPU
16 Channels
Timing Signal Generation Each channel independently user
programmable as TPU function or as
Discrete I/O
Table 1: CPU Port Functions

3 Theory of Operation Digital Board 2763
8Model 7300 Service Manual Rev. 00
The operating frequency of the system clock in the NICO system is 24.117 MHz. It is
generated by an internal VCO (Voltage Controlled Oscillator) derived from Y1, a
32.768KHz watch crystal, and is software programmable. The Timing Processor Unit
(TPU) co-processor of the MC68332 provides complex timing functions generated from
the system clock. This feature is utilized to control the precise timing required for the
acquisition of the End Tidal Carbon Dioxide (etCO2) and saturation (SpO2) signals.
The TPU is also used to generate the PWM (Pulse Width Modulation) control for the
Capnostat Case and Detector heaters, and to provide the frequency generation for the
audio tones. See Tables 2 and 3
QSM
4 Synchronous Serial
Chip Selects & one
asynchronous serial
channel
Serial Communications Port:
QSPI: Queued Serial Peripheral
Interface
SCI: Serial Communications
Interface
QSPI chip selects independently user
programmable, can be used as
Discrete I/O or decoded to create up
to 16 chip selects. SCI transmit can
be programmed as Discrete I/O
Background Mode System debugging Allows an appropriate external device
to control the microprocessor and
system
C Chip Selects D0: CSBOOT* Data Width, 8 or 16-
bit
D1: CS1*-CS3* or BR*,BG*,BGACK*
D2: CS3*-CS5* or FC0-FC2
D3-D7: CS6*-CS10* or A19-A23
E Bus Control D8: Control Signals or Discrete I/O
F MODCK and Interrupts D9: MODCK & IRQ or Discrete I/O
Signal Name Function / Timing
CO2AZ Auto Zero Clears the Sample/Hold circuitry prior to data
acquisition.
Active High, 90 us
CO2PWENB Pulse Width Enable Defines the active time for both phases of the bipo-
lar source pulse, used for pulse width protection
circuitry.
Active High, 810 us
SRCDRV0 Source Drive 0 First source drive signal.
Active High, 405 us
CO2CSHL Current Sample/Hold Enables circuitry for source current measure-
ment. Sample is taken when SRCDRV0 is active.
Low = Sample, 90 us, High = Hold
SRCDRV1 Source Drive 1 Second source drive signal delayed for 10 micro-
seconds after SRCDRV0 ends.
Active High, 395 us
CO2SSH Signal Sample/Hold Enables circuitry for CO2and Reference channel
data acquisition.
Low = Sample, 90 us, High = Hold
CASEPWM Case Heater PWM PWM control for the case heater servo
Table 2: TPU Timing Generation for the etCO2subsystem
Table 1: CPU Port Functions

Digital Board 2763 Theory of Operation 3
Rev. 00 Model 7300 Service Manual 9
To help reduce and suppress the radiation of electromagnetic interference, ferrite filters
(L1-L11) have been placed on clock signals with fast rise and fall times. Other digital
signals, including address and data lines, are rise-time limited by the addition of small
valued resistors and / or capacitors. In addition, good EMI/EMC design techniques
have been incorporated in the component layout and printed circuit board manufacture.
Table 4 lists the chip select, control and discrete I/O functions for the NICO system
module. On power-up, Ports E and F are programmed as discrete inputs by pulling
down their controlling data lines, DB8 and DB9. After power-up, the software sets up
each pin function individually and performs a series of self-tests to check the integrity
of the system. During this period, the MPU holds the SYSUP line low which keeps the
system in the initialization state. The state of configuration inputs on Port E (CNFG0,
CNFG1 and CNFG2) and on data input buffer IC10 (see sheet 2 on 2763-03 schematic)
(JP1, JP2, JP2, JP4, TP4, TP5 and TP6) are read. These inputs allow the software to
identify different operating conditions, such as Manufacturing Diagnostic Mode, or to
recognize different hardware configurations. After the initialization period is complete
and all system functions have been set, the MPU brings the status signal SYSUP high,
indicating that the system is ready for patient monitoring operation.
DETPWM Detector Heater PWM PWM control for the detector heater servo
TOUT1, TOUT2 Tone Generation Variable frequency outputs to generate system
audio
Signal Name Function / Timing
ASAMPL Auto Zero Clears the Sample/Hold circuitry prior to data
acquisition.
Active Low
RDLEDL Red Channel LED control pulse Defines the active time for the Red LED. Active
Low
IRLEDL Infra-Red Channel LED control pulse Defines the active time for the Infra-Red LED.
Active Low
RSAMPL Red Channel Sample/Hold Enables circuitry for the Red Channel signal mea-
surement. Sample is taken when SRCDRV0 is
active.
Low = Sample, 90 us, High = Hold
ISAMPL Infra-Red Channel Sample/Hold Enables circuitry for the InfraRed Channel signal
measurement. Sample is taken when SRCDRV0
is active.
Low = Sample, 90 us, High = Hold
Table 3: TPU Timing Generation for the SpO2subsystem
Port Pin Functions System Signal
Name1
I/O Comments
Table 4: Chip Select, Control and Discrete I/O
Table 2: TPU Timing Generation for the etCO2subsystem

3 Theory of Operation Digital Board 2763
10 Model 7300 Service Manual Rev. 00
CDATA0thru
DATA7
O D0-D7 pulled high, Pins are Chip Select
on power-up
CSBOOT* ROMOEL O Program PROM Chip Select
Word (16-bits) wide mode, D0 = HIGH
CS0* / BR* UBRAMWRL O Upper Byte SRAM Write Enable
Allows for byte (8-bit) or word writes
CS1*/ BG* LBRAMWRL O Lower Byte SRAM Write Enable
Allows for byte (8-bit) or word writes
CS2* / BGACK* SRAMOEL O SRAM Read Enable, Word
CS3* / PC0 / FC0 ROMWRL O FLASH PROM Write Enable, Word
CS4* / PC1 / FC1 UARTCSL O High Speed quad UART Chip Select
CS5* / PC2 / FC2 BOOTWE O Port C Discrete Output, prevents
unintentional writes to FLASH EPROM.
This signal must be asserted before
ROMWR* in order to overwrite the FLASH
CS6* / PC3 / A19 A19 O High Address line A19
CS7* / PC4 / A20 RTCCSL O Real Time Clock Chip Select
CS8* / PC5 / A21 DISPCSL O EL Display Chip Select
CS9* / PC6 / A22 VRAMCSL O Video Memory Chip Select
CS10* / ECLK /
A23
CASCADEL O Cascaded Chip Select for Additional
Parallel Peripherals
E DATA8 O D8 pulled low, Discrete I/O on power-up
DSACK0* / PE0 CNFG2 I Configuration Switch 2
DSACK1* / PE1 DS1L I Data and Size Acknowledge 1*
AVC* / PE2 CNFG0 I Configuration Switch 0
RMC* / PE3 CNFG1 I Configuration Switch 1
DS* / PE4 DSL O Data Strobe
AS* / PE5 ASL O Address Strobe
SIZ0* / PE6 SIZ0 O Signifies current operation is 8-bit data
SIZ1* / PE7 CNFG2 I Configuration Switch 2
R/W* RDL O Data Read Strode
WRL O Data Write Strobe
Table 4: Chip Select, Control and Discrete I/O

Digital Board 2763 Theory of Operation 3
Rev. 00 Model 7300 Service Manual 11
3.2.2 Background Mode Debugging and Application Development
Refer to sheet 1 on 2763-03 schematic.
Background debugging of the system during applications development or during
system testing is possible by connecting an appropriate external device (emulator or
debugger) to header J1. The signals present on this header enable an external device
to halt the current microprocessor bus activity. This turns control of the microprocessor
system over to the external device, placing the microcontroller into Background
Debugging Mode. In this mode, the internal MPU registers can be viewed and altered,
special test features can be invoked and the system’s memory, and peripherals can be
read and written to.
Refer to sheet 2 on 2763-03 schematic.
In addition to the inherent debugging capabilities of the microprocessor, the digital
board also contains circuitry to monitor events during application development. Output
latches IC15 and IC17 along with Profiling header J4 are used to determine CPU
utilization during system development, latching various status bits out on the header.
3.2.3 System Memory
Refer to sheet 1 on 2763-03 schematic.
A 16-bit wide data path is used for FLASH PROM and SRAM transfers to maximize
system throughput. Non-volatile memory, used for the storage of the boot-up and main
program code, is contained in IC4, a 1024K x 8-bit, 5V FLASH ROM. To initiate the
data transfer process, the MPU brings the ROMOEL output signal LOW, causing a
word of program data stored in the FLASH ROM to be sent out on the data bus from
the appropriate memory address. Program data may be updated by commanding the
device to erase a block of its present programmed data then using the ROMWRL signal
to place new program data into the address specified by the MPU. The FLASH ROM
is internally protected from unintentional overwrites of the boot code by requiring an
independent signal, BOOTWE, going active in addition to ROMWRL. The BOOTWE
line must be high prior to writing new boot code into the FLASH device. Two 128K x 8-
bit Static RAMs (IC3 and IC6) contain volatile data storage for use as a temporary data
scratch pad during system operation and for recording patient trend information. To
F DATA9 O D9 pulled low, Discrete I/O on power-up
MODCLK / PF0 LED O LED CPU Activity Indicator
IRQ1* / PF1 SYSUP O System Initialization Complete
IRQ2* / PF2 CSOFTOT O Case Heater Over Temperature Shut
Down
IRQ3* / PF3 DSOFTOT O Detector Heater Over Temperature Shut
Down
IRQ4* / PF4 UARTIRQL I External UART Interrupt
IRQ5* / PF5 EXTDCIN I Indicates external AC MAINS power
operation
IRQ6* / PF6 PWRDWN O System power down enable
IRQ7* / PF7 NMIL I Non-Maskable Interrupt
1.Signal names with an “L” suffix are active low signals.
Table 4: Chip Select, Control and Discrete I/O

3 Theory of Operation Digital Board 2763
12 Model 7300 Service Manual Rev. 00
retain patient trending data during periods of power down, the SRAMs are battery
backed to retain their contents. A 2.5 Volt level VBACK generated from the main
battery via IC30 on the 2764 Power Board, is supplied when the system is turned off
and removed from the AC MAINS. During this battery backed-up state, transistor Q1
keeps the chip enable control line of the SRAMs high and in a low power, inactive state.
This forces the SRAMs data bus to a high impedance state, isolating the parts from the
rest of the system. True non-volatile storage for system parameters is provided by a
serial EEPROM (IC8), which has the ability to retain programmed information in the
absence of power.
3.2.4 User Interface Control Circuitry
Refer to sheet 3 on 2763-03 schematic.
The user interface features a high contrast, 320 row by 240 column Electroluminescent
Display module. Patient and system information is presented in both graphical and
textual formats organized into several screen configurations. An integrated display
controller, IC19, works in conjunction with the MC68332 MPU, and provides the
necessary timing signal generation and housekeeping functions to display the visual
information generated by the system. Programmable logic device IC2 is designed to
condition the logic signals between the MPU and display controller, making sure that
the critical timing specifications of the two devices are met. SRAMS IC18 and IC22
provide video RAM storage for the display system. In addition to buffering the signals
for the display interface, CPLD IC2 also decodes chip selects for the system input
buffers and output latches off of CASCADEL. If required, IC2 can be reprogrammed
in-circuit using header J9.
A 5-switch silicon keypanel and multifunctional rotary encoder provide operator control
of screen selection, patient data entry, and user selectable input. The keypanel also
contains several LEDs which represent various system conditions such as input power
status (AC or Battery) and alarm state. Control of the user interface is generated from
the CASCADEL chip select signal along with the appropriate address line state and
WRL signals from the microprocessor. IC10 and IC13 (sheet 2 on schematic) are input
buffers, which read in the present state of the keypanel and rotary encoder. Depressing
a key or activation of the encoder causes the signal line associated to be pulled low, in
contrast to its normally high state. Input buffer IC14 provides a latched output for
controlling the front panel LEDs as well as several other latched control outputs.
To supplement the visual indicators associated with the membrane keypanel and
display, an audio output signal is generated to provide an additional mode to convey
information to the user. The TPU processor of the MC68332 (TOUT1 and TOUT2) can
generate two-tone frequencies. These signals are fed into separate reference inputs
of the Quad 8-bit DAC, IC20, providing a means for independently attenuating each
signal under CPU control. From the DAC, the individual signals are summed together
by IC21B and filtered by L11 and C50. Audio amplifier IC23 drives the system speaker
to produce system audio. Inverter IC7F, controlled by the SYSUP signal from the MPU,
disables the audio amplifier until system initialization has been completed. DAC IC23
also supplies an output voltage level SPO2VLED to set the current gain of the
saturation drive circuit which is found on the NICO Power PCB, 2764-01. The circuitry
associated with the DACB output (including IC21A, Q3 and J6) is presently not used.
3.2.5 Real Time Clock, Power on RESET Generation and Glue Logic
Refer to sheet 2 on 2763-03 schematic.
Time keeping for date and time stamping of patient trend information is provided by
Real Time Clock IC16. This device contains a built in crystal for precise time and date

Power Supply 2764 (Power Supply and Communications) Theory of Operation 3
Rev. 00 Model 7300 Service Manual 13
measurement. The NICO system has been designed and tested for Y2K compliance.
In the absence of digital power, the time keeping function is maintained by the battery
backed-up supply, VBACK.
On power-up, the system is forced into a RESET state by IC9 (sheet 1 on schematic).
This chip creates the master active low system reset signal SRST*, holding up system
initialization until a stable 5 VDC logic level is maintained. An inverter is used to
generate RESET for devices that require an active high reset signal.
3.3 Power Supply 2764 (Power Supply and Communications)
3.3.1 Serial Communications UART
Refer to sheet 3 on 2764-03 schematic.
To enable serial communication with up to three external devices simultaneously, a
Quad UART (Universal Asynchronous Receiver/Transmitter), IC14, is provided for
buffered high-speed data communication. The connection to external, non-patient
contact-type devices is electrically isolated from the patient applied sections by optical
data couplers (IC16, IC17, IC21, IC23, IC26) and isolated winding off of the power
supply flyback transformer, T1. Transceiver IC13, located on the patient-isolated
circuit, provides signal translation between the system’s TTL logic level and the RS-232
level requirements. Serial Ports A and C (J1 and J3) are configured for a simple 3-wire
(Transmit, Receive and Ground) connection, while Serial Port B (J2) has additional
hardware handshaking capabilities. Connection to an external device is through a null-
modem type of interface cable. The fourth UART channel is available on internal
connector J5 for future product expansion. In addition, the system is capable of
outputting four channels of analog output data through IC22 and receiving four
channels of analog input through buffer amplifiers IC18 and A/D Converter IC20 on
connector J4.Voltage reference IC19 supplies the analog I/O circuitry with a stable
voltage level. Connector J4 allows sensing of external cable connection by shorting
pin 15 (IOSNSE) of the external cable to ground. Refer to Tables 5 to 8 for the pinout
and signals of interface connectors.
J1
Pin Number Signal Function
1 NC No Connection
2RxC Serial Channel A Receive
3TxC Serial Channel A Transmit
4 NC No Connection
5Isolated Ground Non-Patient Signal Ground
6 NC No Connection
7 NC No Connection
8 NC No Connection
9 NC No Connection
Table 5: Serial Channel A, 9-pin D-subminiature connector located on the rear panel

3 Theory of Operation Power Supply 2764 (Power Supply and Communications)
14 Model 7300 Service Manual Rev. 00
J2
Pin Number Signal Function
1 NC No Connection
2 RxB Serial Channel B Receive
3 TxB Serial Channel B Transmit
4 NC No Connection
5 Isolated Ground Non-Patient Signal Ground
6 NC No Connection
7 RTSB Request to Send Channel B, Hardware Handshake
Output
8 CTSB Clear to Send Channel C, Hardware Handshake Input
9 Isolated Power Power
Table 6: Serial Channel B, 9-pin D-subminiature connector located on the rear panel
J3
Pin Number Signal Function
1NC No Connection
2RxA Serial Channel C Receive
3TxA Serial Channel C Transmit
4NC No Connection
5Isolated Ground Non-Patient Signal Ground
6NC No Connection
7NC No Connection
8NC No Connection
9NC No Connection
Table 7: Serial Channel C, 9-pin D-subminiature connector located on the rear panel
J4
Pin Number Signal Function
1Isolated
Ground
Non-Patient Signal Ground
2 ADCIN0 ADC Input Channel 0
Table 8: Analog Connector, 15-pin D-subminiature connector located on the rear panel