May 25, 2005 6881096C74-B
3-12 Theory of Operation: Radio Power Distribution
3.3 Radio Power Distribution
This section provides information on DC power distribution in XTL 5000 radios. In the XTL 5000
radio, power is distributed to three boards: the main board, control head, and secure interface board.
Power for the radio is supplied by the vehicle’s 12-V battery. When using a desktop adapter unit, an
external DC power supply can be connected to replace the vehicle’s battery source.
A+ (referred to as incoming unswitched battery voltage) enters the radio through the rear RF power
amplifier connector (J0950) and is the main entry for DC power. The second path, through J2, pin 25,
provides ignition sense to inhibit radio turn-on when the ignition switch is off.
When the control-head On/Off button is turned on, the three 9.3-V regulators power on the controller
section, the RX/frequency generation unit (FGU) section, and the TX section. See Figure 3-11 for the
UHF Range 1 and UHF Range 2 bands or Figure 3-12 on page 3-13 for the VHF and 700-800 MHz
bands.
Figure 3-11. DC Voltage Routing Block Diagram (UHF Range 1 and UHF Range 2)
VCC5
9.3V_FGU
9.3V_TX
GPIO
KEYED_9.1_EN
A+
SW_A+
UWW_5V
On/Off
Controller Section RX / FGU Section
Control Head
TX Section
J0401
A+
19, 21
SWB+
17
IGN
20
18
25
20, 22
24
SWB+
J0402
J2
J0950
9.3V
Regulator
U0500
9.33V
Regulator
U0950
9.3V
Regulator
U0951
Switch
3.0V
Regulator
U0962
2.85V
Regulator
U0501
1.85V
Regulator
U0507
1.55V
Regulator
U0502
3V
Regulator
U6002
3V
Regulator
U6750
FET
Q0503
UNSW
5V Circuit
VR0500, R0507
SIOIC
5V
Regulator
U0503
5V
Regulator
U0505
DRV_9.3V
9.3V
Regulator
U5570
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