Motorola MTM700

4.1 - 16 MTM700 Mobile Radio / Detailed Service Manual THEORY OF OPERATION (400 MHz)
Controller Section
For the Controller Section Block Diagram see Figure 5.
This section describes the related circuits as follows:
• DC Power Distribution
• Microprocessor
•Host Memories
• Radio Audio System
DC Power Distribution
Figure 6 DC Power Distribution Diagram
DC Power Input
The DC power of nominal 13.2 volts enters the radio at connector J0301. Diode VR0300 acts as
protection against transients and wrong polarity of the supply voltage. The supply voltage is fed
directly to the RF PA, through the 3A fuse F0302 to the audio circuitry, expansion head and control
head, and through the 3A fuse F0300 to regulators U0300, U0301, U0302, and the ON/OFF and
VSTBY circuitry. The fuses protect the board from over current in case of a short on the connector
pins or circuit failure.
HDI Module
ABACUS
FracN
Expansion
Hea d
Controller
RF PA
Audio
I/O
VCOBIC
RX-VCO
FE + Mixer IF
RedCapFlashRAM
ADDAG
TX
ACCESSORY
CONNECTOR
20-PIN
13,2V
A+
4.6V
VSF
5V
9,3V
9,3V
9,3V
Escort
TX-VCO
3V3_DIG
Q0305
Hea d D
5V
Regulator
LP2 951
3V_DIG
U0305
LP2 951C
SPI
UART
Option
LNODCT
3V_TX
U0307
MC33275
5 V_TX
U0304
LP2951C
1.8 V
U0306
LP2 951C
ON/OFF
Circu it
SW B+
U0302
LM2941
9V3_TX
U0300
LM2941
3V3_FN
U5321
LP2980
5V_FN
U5322
ADP3300
Digital_3V3
U5103
LP2980
Analog_3V3
U5102
LP2980
Ref.
Voltage
9V3
U0301
LM2941
SW B+
3V_TX
3,3V_DIG
3 V
Regulator
LP2951
SW B+
Regulator
LP2941
5VD
U0303
78M05
5 V
9,3V
ON / OF F
9,3V_TX
13,2V
5V_TX
ON/OFF V STBY
PC I C
3 V_DIG
Fuse
F0302
Fuse
F0300