Philips 32PW9618 Service Manual page 145

Circuit Descriptions, Abbreviation List, and IC Data Sheets
Synthesizer and Local Oscillator
+8V
2616
2p7
7603
BFR92A
OSCILLATOR
The internal circuitry of the 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
6 2
I C-BUS
SCL
TRANSCEIVER
5
SDA
11
3-BIT 3-BIT 4-BIT LATCH
ADC
ADC INPUT
PORTS OUTPUT PORTS
POWER-ON
RESET
7
P3 P2 P1 P0
Figure 9-24 Block diagram TSA5060A
The TSA5060A is software controlled via the I2C bus by the
PIC12C508 microcontroller.
There is no hardware version recognition foreseen but the
version can be read out from the PIC12C508 microcontroller.
There is a different software code for the 433, 864, or 914 MHz
version.
The reference quartz crystal is 4 MHz and is divided to a lower
reference frequency of 200 kHz or 100 kHz (depending on the
version). The PLL filter is passive and includes 2625, 2626,
3615, 3611, and 2612. The transistor 7604 is part of the PLL
current source, and allows connection to higher supply
voltages as +5V.
The local oscillator (LO) is a common base transistor (7603)
that is oscillating at the fundamental frequency. The frequency
is tuned by the varicap 6601 until the tuning voltage is in the
range of the loop filter (between 0.5 and 7 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.
2613
4p7
+8V
7606
BC847B
Figure 9-23 Synthesizer circuit
3
XT/COMP
LOCK
DETECT
DIGITAL PHASE
COMPARATOR
CHARGE PUMP
1
CP
2-BIT
LATCH
16
AMP DRIVE
12
V CC
15
GND
MODE
AND
CONTROL
LOGIC
TSA5060A
8 9 10
FCE717
CL36532008_071.eps
010503
SYNTHESIZER
7605
TSA5060ATS
16 1
DRIVE CP
15 2
GND XTAL
2623
14 3
RFB XT|COMP
1p0
13 4
RFA AS
5617
12 5
VCC SDA
11 6
ADC SCL
10 7
P0 P3
9 8
P1 P2
IF Amplifier
1706
IF
3709
I
180R
GND
SFELA
Figure 9-25 IF amplifier circuit
The mixer output signal is filtered by two ceramic IF filters. An
IF amplifier (7707) is reducing the loss introduced by these
filters.
EM6E 9.
+8V
F749
3615
560R F749
2625 2626 3611
220R
2u2 220n
7604
BC847B
1609
2624
18p
AT-51
4M
+8V
F709
F709
IF AMP
1707
I O
GND
7707
SFELA
O
10M7
BFS20
10M7
CL36532008_082.eps
EN 145
DA
CL
CL36532008_079.eps
130503
290403