Motorola MTM700, Detailed Service Manual

Page: 50 / 328

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
AB ACUS
FracN
Expansion
Head
Controller
RF PA
Audio
I/O
VCOBIC
RX-VCO
FE + Mixer IF RedCa p
Flash RAM
ADDAG
TX
ACCESSORY
CONNECTOR
20-PI N
13,2V
A+
4.6 V
VSF
5 V
9 ,3 V
9 ,3 V
9 ,3 V
Escort
TX -VCO
3V3_DIG
Q0 3 0 5
Head D
5 V
Regulator
LP2 951
3 V_ DIG
U0305
LP2 951 C
SPI
UART
Optio n
LNODCT
3 V_ TX
U0 3 0 7
MC3 3 2 75
5 V_ TX
U0 3 0 4
LP2 9 5 1 C
1.8 V
U0306
LP2 951 C
ON/OFF
Circu it
SW B+
U0302
LM2941
9 V3 _ TX
U0 3 0 0
LM2 9 4 1
3 V3 _ FN
U5 3 2 1
LP2 9 8 0
5 V_ FN
U5 3 2 2
ADP3 3 0 0
Digital_3V3
U5 1 03
LP2 9 8 0
Analog_3V3
U5 1 02
LP2 9 8 0
Ref.
Voltage
9 V3
U0 3 0 1
LM2 9 4 1
SW
B
+
3 V_ TX
3,
3V
_D
IG
3 V
Regulator
LP2951
SW B+
Regulator
LP2941
5 VD
U0303
78M05
5 V
9 ,3 V
ON / OFF
9 ,3 V_ TX
13,2V
5V
_T
X
ON/OFF VSTBY
PCIC
3 V_ DIG
Fuse
F0302
Fuse
F0300