Controller Dc Power Distribution; Figure 3-45. B+ Routing For Controller Section - Motorola ASTRO Digital XTL 5000 Detailed Service Manual

Theory of Operation: Controller Section
3.8.2

Controller DC Power Distribution

Figure 3-45 illustrates the controller DC power distribution circuitry.
The A+ power for the radio is derived from the 12-V battery, which is applied to the main board
through connector J0950. This A+ voltage is routed to the control-head connector, J0401, pins 19
and 21, to the control head.
A power FET (Q51) provides the means of controlling the main power source (SWB+) by the on/off
switch. SWB+ is routed back to the main board through connector J0401-17 and out the rear
connector, J2-24.
SW_B+ turns on controller FET switch Q0503, which supplies SW_A+ to regulator U0500. This 9.3-
V regulator powers up the main 5-V controller regulator U0503. The 5-V supply powers on all four
controller regulators:
• U0962 (3.0 V) for the power control section
• U0503 (2.85 V) for the controller and daughtercard I/O
• U0507 (1.85 V) for the memory
• U0502 (1.55 V) for the microprocessor core.
The SW+5-V regulator is the main power source for the controller.
Vcc1.5 = 1.55V
Vcc1.8 = 1.85V
Secure IF
Board
J0500
Vcc2.8 = 2.85V
ADC
U0953
Vcc = 3.0V
Unsw 5V = 5.0V
On the secure interface board, U800, Q802, and Q803 provide SWB+ to the encryption module (if
equipped). The SWB+ and UNSWB+ encryption voltages both originate from the secure interface
board and are fed to the encryption module via J0701 and J0501.
It should also be noted that a system reset is provided by the undervoltage detector, U0504. This
device brings the system out of reset on power-up, and provides a system reset to the
microcomputer on power-down.
6881096C74-B
PATRIOT
CORE
U100
8MB
PATRIOT
FLASH
EIM
U102
U100
Patriot I/O
USB Mic Amp Ckt
SSI, SPI,
XCVR U0201, U0202,
BBP, UARTs
U0304 Codec-U0200
Power Control
DAC
SW_B+
Digital POT
U0959
U0952
EMERG
Timer
U0506

Figure 3-45. B+ Routing for Controller Section

3V, 2.8V,
SB9600
1.8V, 1.5V
Circuit
Regulators
Vcc5 = 5.0V
IMB
SRAM
U103
Modulation
Misc. gates,
DAC-U0900,
buffers, etc.
Urchin-U0901
U100
Rear Acc'y Conn
(J2/J0402), Radio Turn
On/Off (Q0503 circuit),
Secure IF Board (J0501)
Audio PA
U0204
A+
Audio PA RS232
VIP's Digital POT Transceiver
U0206 U0305
5V
9.3V - Controller
Regulator
U0503
FET (Q0952),
9.3V - TX
Power Ctrl
Loop
RX/FGU
VCO
5V Reg
9.3V - FGU
9V
SW_A+
Regulators
U0950, U0951
U0500
Secure IF SW_A+
Control
Board FET
Head
J0500
Q0503
MAEPF-27892-O
May 25, 2005
3-65