Mindray Passport 5-Lead, Service Manual

Page: 242 / 544

Block Diagrams Theory of Operation
2 - 40 0070-00-0420 Passport 5-Lead, 5L, LT, XG Service Manual
Signal Isolation
The interface signals to and from the Oximeter Modules are isolated by five optocouplers,
U7 through U11. The low duty cycles of the signals holds the power requirements to
reasonable levels.
Schmitt trigger inverters are used at the optocoupler outputs due to the slow rise and fall times
of the couplers. This provides a clean output edge with no bouncing and reduces timing
skew. The U11 output requires no such Schmitt buffer due to debouncing hardware built into
the U1 microcontroller. Other inverters are used in the circuits to provide the necessary
inversions for proper signal polarity and to force the optocouplers normally off.
All of the U1 signals to and from the Nellcor Module to be normally high with the exception
of CTS*. This signal should be normally active low and only become inactive if Nellcor
Module data transmissions must be suspended.
2.2.4 CPU Board
Overview
The Passport CPU board is the central controller for the Passport transport monitor. The
functions that this module must support are: Front end and NIBP serial communications, LCD
control, Trend functions, Alarm functions, SpO2 parallel communications, Recorder interface,
Speaker, Real time clock, Keypad monitoring, RS-232 interface, D/A, and miscellaneous
diagnostics.
FIGURE 2-17
CPU Board Block Diagram
PARALLEL
SaO2
MODULE
INTERFACE
(64)
J65
ADDRESS
BUFFER
U8, U9, U10
BIDIRECTIONAL
DATA BUFFERS
U7
68302
MICRO-
CONTROLER
U1
DIGITAL PERIPHERALS
SERIAL
FRONTEND
MODULE
INTERFACE
(10)
J64
+5V
+15V
-15V
GND
FRST
+5V
GND
VDC
PGND
INVERTING
BUFFERS
U31
RS-232
BUFFERS
U31
128K X 16
LOW POWER
SRAM US, U3
WATCHDOG/
BATTERY
MANAGER
U21
SERIAL
EXTERNAL
INTERFACE
(16)
J66
AIN
ECG
DSYNC
GND
SCC1
SCC2
RS-232
BUFFERS
U31
SERIAL
NIBP
MODULE
INTERFACE
(26)
J62
PBRST*
NRST*
+5V
+15V
-15V
+12V
GND
PARALLEL
AR-42 RECORDER
INTERFACE
U12, U13, U14
SERIAL
64 X 16
EEPROM
U4
SERIAL
RTC
U20
BT1
23-BIT
ADDRESS
BUS
32.768
KHz
Y2
RCRST
GND
+5V
PGND
+12V
16-BIT
DATA BUS
Y1
16.5888MHz
RST*
FRST
NRST
RCRST
DSYNC
BLEN
TIMER2
CPU
DISPLAY CONTROLLER
ANALOG PERIPHERALS
16-BIT DATASETTE
(50) J61
ADDRESS
MULTIPLEXER
U15
32K X 8
STATIC
VIDEO MEMORY
U6
DATA
BUFFER
U16, U17
SERIAL
11-CHANNEL
8-BIT
A/D
CONVERTER
U32
8-BIT
D/A CONVERTER
U36
DEMULTIPLEXER
U34
8-OUT 4-IN
KEYPAD
INTERFACE
U18, U19
SPEAKER
DRIVER
U37
TONE GENERATOR/
FILTER
J34, U35
ECG OUTPUT
FILTER/BUFFER
U33
FRONT PANEL
INTERFACE
(40)
J68
LCD
VSP
+5V
+12V
-23V
+5V
+15V
-15V
VDC
VSP
+12V
AIN
VSP
POWER
CONNECTOR
(16)
J67
+5V
+15V
-15V
GND
+12V
PGND
VDC
-23V
BLEN
ECG
LCD
V6366
DISPLAY
CONTROLLER
U5
LCD
BUFFERS
U29, U30
11.0592MHz
OSC.
U38
VOLUME
TIMER2
3V LITHIUM BATTERY