Motorola ASTRO XTSTM 4000, Detailed Service Manual

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6871620L01-C May 28, 2008
Theory of Operation: Transceiver Section 3-9
3.1.3.6 Power-Control IC (PCIC) U104
The PCIC, U104, contains all of the digital, and most of the analog, circuits needed to control the
transmitter power amplifier. Host control is through a 3-wire, smart SPI interface. Pin descriptions are
shown in
Table 3-3 .
Table 3-3. Power Control IC (U104) Pin Descriptions
Pin Name Description
1 RFIN Detector voltage input to ALC
2 T1 Test point
3 CI External capacitor for integrator time constant
4 INT Integrator output; control voltage to amplifiers
5 CJ External capacitor for PA rise and fall times
6, 7 VL, CL External capacitor for PA rise and fall times
8 GND1 GROUND
9 F168 Reference clock input, 2.1 MHz
10, 13 QX, CQX External capacitor for voltage multiplier
11, 12 Q, CQ External capacitor for voltage multiplier
14 V10 Voltage multiplier output
15 VG Internal band-gap reference voltage
16 V45 Regulated 4.5 Vdc output
17 V5EXT Power supply input for internal voltage regulator
18 VAR2 Buffered D/A output
19 VLIM Test point for internal D/A No.2 voltage
20 VAR1 Buffered D/A output
21 RS Asynchronous reset input
22 NA Spare pin
23 RX RX/TX mode control-bit output
24 VAR3 Buffered D/A output
25 GND2 GROUND
26 CLK SPI clock input
27 BPOS Power supply input
28 DATA SPI data input/output
29 CEX SPI chip select input
30 TEMP Temperature sensor input
31 RSET External resistor; used to set the temperature cutback rate
32 ANO Switched BPOS output