Siemens TDA5940-2 Datasheet

Video and Sound IF
with V & S SCART

Features

● Features video / sound scart

● Active FM-PLL demodulator

● AF control

● Alignment - free sound IF

P-DIP-24-2

Type Ordering Code Package

TDA 5940-2

Bipolar IC

TDA 5940-2 Q67000-A5144 P-DIP-24-2

Functional Description and Application
Video IF Section

Video IF-broadband amplifier followed by a quasi-synchronous demodulator for negative
modulated IF signals. A Full-SCART interface is included in the video section. A separate video
output after the demodulator permits the installation of one or more sound traps at the input of the
SCART switch. The tuner AGC threshold is set by means of a potentiometer, all other functions can
switched with open collector transistors.

Sound IF Section

FM-IF limiter with FM-PLL demodulator. The AF section has a Full-SCART switch followed by a
volume control. The volume is controlled by an analog voltage.

Application

The TDA 5940-2 is suitable for application in television receivers with Full-SCART.

Semiconductor Group 44 06.94

TDA 5940-2

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
SCART-switch input are connected by means of a sound trap. The SCART switch has two inputs
(for signals from video demodulator and SCART socket) and two outputs (SCART socket and TV
output). 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.

Sound IF Section

The sound IF section incorporates a five-stage, symmetrical limiter amplifier followed by a PLL
demodulator. The AF section contains an analog switch for the Full-SCART interface and a volume
control with AF output.

Semiconductor Group 45

Pin Functions
Pin No. Function

1 Video IF input
2 Video IF input
3 Low-pass capacitor
4 De-emphasis capacitor
5 Audio SCART output
6 Audio output
7 Audio SCART input
8 Audio volume control
9 Sound IF input
10 Ground

TDA 5940-2

TDA 5940-2

11 Video demodulator output
12 Video input at sound trap output
13 Demodulator tank circuit
14 Demodulator tank circuit
15 MUTE control
16 Video SCART input
17 Video output
18 Video SCART output
19 +
20 Ground
21 SCART control
22 AGC-time constant
23 Delayed tuner AGC threshold
24 Delayed tuner AGC output

V

supply voltage

S

Semiconductor Group 46