Motorola CP040

Chapter 1
THEORY OF OPERATION
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
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+
Figure 1-1 DC Power Distribution Block Diagram
SWB+
Fuse
Low Battery
Detect
Antenna
Switch
PA, Driver
PCIC(ALC)
LI Ion
3.3V
Reg.
Audio
Power
Amplifier
ASFIC_CMP
VCOBIC
FRACTN
LCD
Driver
5V
MECH.
SWB+
UNSWB+
Vdda
Accessories
20 pin Connector
Keypad/Option Board
Vddd
MCU, ROM
and EEPROM
Tx
Led
Control
7.5V
Battery
Vddd
Regulator
Vdda
Regulator
5V
Regulator
On/Off
Switch
RF AMP, IF AMP,
RX/TX Buffers
IFIC