Philips 32PW9618 Service Manual page 142

EN 142 9.
Synthesizer and Local Oscillator
+8b
F112
2103
3109
4K7
10u
1105
AT-51
4M
3102
I2C_data
470R
3101
I2C_clock
470R
6101
PLVA2656A
Hole 3.5 mm
0001
1
2
frame
1 2 3 4 5
1107
The internal circuitry of the synthesizer IC (TSA5060A) can be
seen in figure below:
2
XTAL REFERENCE
XTAL
OSCILLATOR DIVIDER
4-BIT LATCH
13
RFA
PRE DIVIDER 17-BIT
14
AMP 1/2 DIVIDER
RFB
1-BIT 17-BIT LATCH
LATCH DIVIDE RATIO
4
AS
2
6 I C-BUS
SCL
TRANSCEIVER
5
SDA
11
3-BIT 3-BIT 4-BIT LATCH
ADC
ADC INPUT
PORTS OUTPUT PORTS
POWER-ON
RESET
P3 P2 P1 P0
Figure 9-18 Block diagram TSA5060A
The TSA5060A is software controlled by the I2C bus
(commands are send directly via the TV slow I2C bus).
To verify whether there is communication between the host
device and the TSA5060A, one can check the supply voltage
of the oscillator transistor 7103 (TP F113). This should be
about 7.5 V in normal conditions when the I2C signal is
interpreted by the synthesiser. If there is improper
communication, the voltage remains at 0 V.
There is version recognition foreseen to discriminate between
433 or 864 MHz units. This feature will automatically load the
correct frequency division words into the synthesiser at starting
up and initialisation of the TV set.
The reference quartz crystal is 4 MHz, which is divided to a
lower reference frequency of 25 or 50 kHz (depending on the
version).
The PLL filter is passive and includes 2103, 2104, and 3107.
The transistor 7102 is part of the PLL current source, and
allows connection to higher supply voltages as +5 V.
EM6E
Circuit Descriptions, Abbreviation List, and IC Data Sheets
SYNTHESIZER
3107
7101
2K2
TSA5060ATS
2104
1 16
CP DRIVE
100n 2102
2 15
XTAL GND
18p
3103 3 14
XT|COMP RFB
1K0
3104
4 13
AS RFA
1K0
5 12
SDA VCC
6 11
SCL ADC
F110 7 10
P3 P0
8 9
P2 P1
2197
220p
Figure 9-17 Synthesizer and local oscillator
3
LOCK
DETECT
DIGITAL PHASE
COMPARATOR
CHARGE PUMP
1
2-BIT
LATCH
16
AMP
12
15
MODE
AND CONTROL
LOGIC
TSA5060A
7 8 9 10
FCE717
CL36532008_071.eps
010503
6102
3110
330R
BB151
7102
BC847B
2106
1n0
F111
The TSA5060A has some output ports:
•
Port P3 (Vosc), used to switch the local oscillator (LO).
•
Port P2 (Vpil), used to switch the pilot.
•
Port P1, used to switch the power amplifier (PA).
XT/COMP
The local oscillator (LO) is a common base transistor (7103)
that is oscillating at half the output frequency. The frequency is
tuned by varicap 6102, until the tuning voltage is in the range
of the loop filter (between 1 and 6 Vdc). If the voltage is outside
this range, then possibly the division ratio is chosen outside the
normal range, or some frequency dependant component
around the transistor is faulty.
CP
DRIVE
V CC
GND
5132
BLM21
4107
2111
2113
6p8
5p6
2101
7103
BFR92A
10n
5101
+5V
100n
2198
220p
3116 F113
100R
2120
1p8
CL36532008_070.eps
290403