Figure 4-8. Frequency Generation Unit Block Diagram (Uhf Range 2); Table 4-12. Lv Frac-N U6751 Pin Descriptions (Uhf Range 2) - Motorola ASTRO Digital XTL 5000 Detailed Service Manual

4-20 Troubleshooting Procedures: UHF Range 2 (450–520 MHz) Band Main Board Troubleshooting
3.0V
5.0V
16.8MHz OSC
3.0V
Regulator
3.0V
U5750
CLOCK
SYN_SEL
U5752
From
Controller DATA
MOD_IN
PHASE
Bias 1
DETECTOR BIAS
Q5750 RX and
Bias 2
Q5751 TX
SFIN
9.3V
SFBASE
SFOUT
8.2V
Super Filter
8.2V
Q5752

Figure 4-8. Frequency Generation Unit Block Diagram (UHF Range 2)

Table 4-12. LV Frac-N U6751 Pin Descriptions (UHF Range 2)

Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
May 25, 2005
3.0V
16.8MHz Reference
to Controller and
Receiver Back End
U5751
VOLTAGE
MULTIPLIER
3.0V
D5750 and
D5751
VMULT3
VMULT4
A
AUX1
B
AUX2
C
AUX3
AUX4 NC
IOUT
IADAPT
C5780
Mod Out
C5779
PREIN
Prescaler Input
Lock
Lock Detect
to Controller
Pin Name Description
AUX2 Auxiliary logic output
AUX3 Auxiliary logic output
AUX4 Auxiliary logic output
LOCK Lock detect—logic high indicates in-lock condition
PD_VDD 3.0-V supply (phase detector)
GROUND Ground (digital)
DATA SPI data I/O
CLK SPI clock
CEX SPI enable line—active low
MODIN Modulation input from controller
VMULT4 Multiplier clock output
VMULT3 Multiplier clock output
VRO 3.0-V supply for reference oscillator warp circuitry
VMULT2 Not used
8.2V
Q5706
U5753
X0
X1 Q5707
X2
X3
X4
8.2V SW
Q5708
LOOP
8.2V SW
FILTER
Q5709
8.2V SW
Q5710
8.2V SW
8.2V SW
Keyed
9.1V
Q5825
TX
TX
INJECTION
Q5826
Injection
7.5V
Q5901
RX
RX
Q5903
INJECTION
Injection
Q5905
8.2V
RF
Q5755
Feedback
6881096C74-B