TDA5950X Datasheet, PDF (2/11 Pages) Siemens Semiconductor Group – Video and Sound IF with FM-PLL Demodulator, AFC and V & S SCART

TDA 5950X
Circuit Description
Video IF Section
The video IF section incorporates a four-stage, capacitively coupled, symmetrical and controlled
amplifier, a limiter with selection and a mixer for quasi-synchronous demodulation of negative
modulated IF signals followed by a video output amplifier. The video demodulator output and the
video switch input are connected by means of a sound trap. The video switch has two inputs (for
signals from video demodulator and from external source) and two outputs. Parallel to the video
output amplifier the video signal is used for generating the AGC voltage. The control circuit is
designed on the integralaction AGC principle, employing a noise-free peak value detector. A
delayed tuner AGC voltage with positive control direction is derived from the AGC voltage via a
threshold amplifier that is set by means of an external potentiometer. An AFC push pull output
current is generated from picture carrier tank circuit.
Sound IF Section
The sound IF section incorporates a five-stage, symmetrical limiter amplifier followed by a PLL
demodulator. The AF section contains an audio switch followed by an output buffer.
Switch Matrix
AUX/RF-Control
(Pin 4)
0
0
1
1
AV-OFF
(Pin 17)
0
1
0
1
Output
(Pin 8 / Pin 19)
muted
IF
muted
SCART
Semiconductor Group
2