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CP-850FX Service Manual
Europe R&D 33
4.5 TDA4470 - MULTISTANDARD VIDEO-IF AND QUASI PARALLEL SOUND PROCESSOR
4.5.1 DESCRIPTION
The TDA4470 is an integrated bipolar circuit for multi-standard video/sound IF (VIF/SIF) signal
processing in TV/VCR and multimedia applications. The circuit processes all TV video IF signals
with negative modulation (e.g., B/G standard), positive modulation (e.g., L standard) and the AM,
FM/NICAM sound IF signals.
4.5.2 FEATURES
- 5 V supply voltage; low power consumption.
- Active carrier generation by FPLL principle (frequency-phase-locked-loop) for true synchronous
demodulation.
- Very linear video demodulation, good pulse response and excellent intermodulation figures.
- VCO circuit operates at picture carrier frequency, the VCO frequency is switchable for L’-mode
- Alignment-free AFC without external reference circuit, polarity of the AFC curve is switchable.
- VIF-AGC for negative modulated signals (peak sync. detection) and for positive modulation
(peak white/black level detector).
- Tuner AGC with adjustable take over point.
- Alignment-free quasi parallel sound (QPS) mixer for FM/NICAM sound IF signals.
- Intercarrier output signal is gain controlled (necessary for digital sound processing).
- Complete alignment-free AM demodulator with gain controlled AF output.
- Separate SIF-AGC with average detection
- Two independent SIF inputs
-
Parallel operation of the AM demodulator and QPS mixer (for NICAM-L stereo sound).
4.5.3 PINNING
Pin Symbol Function
1, 2 V
i, SIF1
SIF1 input (symmetrical)
3 V
SW
Input selector switch
4, 9, 16 GND Ground
5 V
AGC
SIF – AGC (time constant)
6, 7 V
i, VIF
VIF input (symmetrical)
8 C
AGC
VIF – AGC (time constant)
10 R
TOP
Take Over Point, tuner AGC
11 I
tun
Tuner AGC output current
12 V
O, VID
Video output
13 V
SW
Standard switch
14 V
SW
L’ switch
15 C
bl
Black level capacitor
17 C
ref
Internal reference voltage
18 LF Loop Filter
19 V
SW
AFC switch
20, 21 V
VCO
VCO circuit
22 V
AFC
AFC output
23 V
S
Supply voltage
24 V
O, FM
Intercarrier output
25 V
O, AM
AF output – AM sound
26 R
comp
Offset compensation
27, 28 V
i, SIF2
SIF2 input (symmetrical)
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