TDA4452 Datasheet, PDF (2/11 Pages) TEMIC Semiconductors – Video IF Amplifier for Multistandard TV Receiver and VTR Appliances

TDA4452
Pin Description
Pin
Function
1,18 IF input
2 Video switch control
3
VTR input, 1 V_PP
4
VTR output, 2 V_PP
(inverted)
5
Supply voltage V_S
6
Video output, 2 V_PP
7
Video input, after sound trap, 2 V_PP
Pin
8,17
9
10,11
12
13
14
15
16
Function
Ground
Video output, 3 V_PP from demodulator
Demodulator circuit
standard switch B/G-L
Average capacitor standard L
Tuner AGC take over
AGC (tuner control)
IF AGC storage capacitor
Circuit Description
The following functional units are integrated in this
circuit combination for processing multi standard
television IF signals:
The IF signal is supplied to the synchronous demodulator
via a three-stage gain controlled wideband amplifier. A
level detector limits the output voltage of the wideband
amplifier in the event of overdrive.
The required switching carrier for the demodulator is
obtained from the IF signal of the wideband amplifier by
means of a selection and limiter stage. A delay network
is connected upstream of the demodulator in order to
compensate phase differences.
The polarity of the switching carrier at the output of the
limiter stage can be reversed with the standard switch
(Pin 12), with the result that negatively or positively
modulated IF signals appear at the demodulator output
with the same polarity. The demodulated video signal is
filtered and amplified and is supplied to the video output
(Pin 9) via a noise limiter stage.
The standard switch also adapts the operating point of the
video post-amplifier and the IF AGC to the standard
which is to be processed. In the case of standard B/G, the
synchronous peak value acts as the control criterion for
rapid charging and discharge. In contrast, rapid control is
achieved for standard L by charging for ultra white and
discharge by the average (Pin 13) with controlled
reference.
An adjustable control current output (Pin 15) is available
for delayed control of the tuner pre-stage.
A video source switch with 2 inputs is integrated for VTR
applications. The external VTR signal is supplied
capacitively to the input Pin 3 and is clamped to the
synchronous peak value. The second video input Pin 7 is
connected with Pin 9 (video signal from demodulator) via
an external sound trap.
The sound trap must process an attenuation for dc and ac
of 3.5 dB so that the video switch is not overdrived. In
addition, the demodulated video signal is available in in-
verted form as a VTR output signal at Pin 4, independent
of the position of the video switch.
2 (11)
TELEFUNKEN Semiconductors
Rev. A1, 15-Aug-96