Overview; Radio Power Distribution - Motorola Commercial Series Service Information

1.0

Overview

This Chapter provides a detailed theory of operation for the controller circuits in the radio. The
components of these circuits are contained on the Main Board. Refer to the RF sections of this
manual for the component location details and the parts lists of the Controller Circuits.
2.0

Radio Power Distribution

UNSWB+
7.5V
Battery
Fuse
MECH.
SWB+
3.3V
Reg.
Low Battery
LI Ion
PA, Driver
PCIC(ALC)
Figure 1-1 illustrates the DC distribution throughout the radio board.
Battery voltage enters at connector J301 and is routed through fuse F301 to become USWB+.
VR301 protects against ESD, and D301 provides reverse polarity protection. This voltage is routed
to:
FET switch Q170 in the TX power control circuit (turned on during transmit)
TX power amplifier module U110 (via R150)
input pins of regulators U310, U320 and U330
FET switch Q493 (turned on whenever the radio is on)
on-off switch S444 (part of on-off-volume control) to become SWB+
Audio
Power
Amplifier
SWB+
Control
On/Off
Switch
Detect
Antenna
Switch
Figure 1-1 DC Power Distribution Block Diagram
THEORY OF OPERATION
Vdda
Vdda
Regulator
Vddd
Vddd
Regulator
MCU, ROM
Tx
and EEPROM
Led
5V
Regulator
5V
Chapter 1
Accessories
20 pin Connector
Keypad/Option Board
LCD
ASFIC_CMP
Driver
RF AMP, IF AMP,
RX/TX Buffers
IFIC
FRACTN
VCOBIC