Chapter 3 Dc Power Distribution; Dc Regulation And Distribution; Figure 3-1. Dc Power Distribution Block Diagram - Motorola EP350 Service Manual

Chapter 3 DC Power Distribution

3.1

DC Regulation and Distribution

A block diagram of the DC power distribution throughout the radio is shown in Figure 3-1.
7.5V
Battery
Battery voltage enters at connector J602 and is routed through SW/VOL1 to become SWB+.
This voltage is routed to:
• SW/VOL1
• TX power amplifier Q403 (via R417)
• APC circuit U401
• RX audio power amplifier U601
• 5V regulator (U505)
• 3.3V regulator (U506)
• Voltage divider R153/R154, a microprocessor A/D input which measures battery voltage
• Key PCB
SWB+
Mech SW1
PA
APC
Driver,
Pre-driver

Figure 3-1. DC Power Distribution Block Diagram

5V
Vdd
Regulator
Voltage
Doubler
10V
Charge
Pump
3.3V
Vdd
Regulator
Key PCB
Low Batt.
detector
Audio
Amplifier
VCTCXO
Audio filter
½ Vcc
VCO
RX B+
TXVB
MCU, EEPROM
PLL IC
Digital potentiometer
DTMF IC
LCD Driver