Nellcor N-180 Service Manual page 29

N-180 Pulse Oximeter Service Manual
The communication data link is bi-directional-asynchronous and serial.
Transmissions are checked for errors; the presence of an error
isevidence of a hardware problem. No transmission retry capability is
included.
m | Oximetry Support Circuits:
Oximetry module support circuits consist of 80C522 micro controller US
(figure FO10-1, sheet 7 of 7), ROM U6, and RAM 012, all served by octal
latch U2. Serial-to-parallel shift register U16 outputs parallel data for
the DACBUS. The oximetry module timing is set by an 11.0952 MHz
' erystal-controlled oscillator. Sections U11 and U17 perform reset and
buffer functions for the communication link.
m Power:
The following power is derived from the CPU PCB.
Volts Tolerance Current maximum (ma)
+5 4% - 78.05
+15 5% 8.21
-15 15% 0
6 15% 5.29
Microcontroller
U5 80C552 U16 DAC BUS
YI
[SerauParalel
11,0052 Glock voPo(0.7) ka Register
and =
i Address and =
Timing Data Lines Г |
Chip Reference
vO Pa (0..7)
uz
us
and Supply Function =
Voltage Inputs Control Lines = ROM
— Latch E
COMPARE 1 —İ VO PS (0..7) VO PS (0..7) =
COMPAREZ ューーー] =
Data and Test Memory | =
AD 2) Signal Inputs Address Lines
U12
RESISTORS <—— VO PS (0..7) VO P3 (0..7) =
SATIN — Host =
IRLED «——
Analog Control Communications
| RAM
REDLED «——| | Function Lines Control =
EST =
- Reset Circuit = - - =
Reset »—— — U11DU17D.EF
ADC RESET"
m
2 Processor
TXD PCB
—— CTS*
N-185/060
Figure 3-6: Oximetry Module Support Circuits
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