Motorola CP160 Detailed Service Manual page 46

2-6
IC Designator
U451
ASFIC_CMP
Pin Pin Function
1 VDD for analog circuits
2 DISC audio input
3 Ground for analog circuits
4 DACU output
5 DACR output
6 DACG output
7 VOX peak detector output
8 PLCAP for DC integrator
9 SQIN
10 Universal audio input/output
11 VDD for DACs
12 SQCAP
13 GCB2 general purpose output
14 GCB1 general purpose output
15 GCB0 general purpose output
16 Squelch channel activity output
17 Squelch detect digital output
18 PL/low speed data I/O
19 High speed data I/O
20 Chip select
21 Serial clock input
22 Serial data input
23 Ground for clock synthesizer
24 Loop filter cap for clock syn
25 PLCAP2 for LS integrator
26 Not used
27 Vdd for clock synthesizer
28 Clock synthesizer output
29 1200 Hz ref for MDC decode
30 GNDDO
31 Ground for digital circuits
32 Vdd for analog switches
33 Vdd for digital circuits
34 16.8 MHz master clock input
35 GCB3 general purpose output
36 TX audio return from option
37 GCB4 general purpose output
TROUBLESHOOTING TABLES
DC Voltage Comments (Condition)
3.00
1.34 From U510
GND
0
0
2.38 (typ) Power set (TX mode)
2.91
0.40
0.01
0
4.95
0
0 Audio PA_EN (unsquelched)
0
3.00 BW select (25 kHz mode)
0 To U401-84
0 To U401-83
1.50
3.00
3.23 From U401-2
0
3.23
GND
0.74
1.17
0
3.00
1.70
3.00
GND
GND
4.96
3.00
1.54
3.00 Internal MIC enable
0
0