Video and Sound IF
with V & S SCART
Bipolar IC
TDA 5940-2
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.
Type
Ordering Code
Package
TDA 5940-2
Q67000-A5144
P-DIP-24-2
Semiconductor Group
44
06.94
Features
q
Features video / sound scart
q
Active FM-PLL demodulator
q
AF control
q
Alignment - free sound IF
Semiconductor Group
45
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
46
TDA 5940-2
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
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
+
V
S
supply voltage
20
Ground
21
SCART control
22
AGC-time constant
23
Delayed tuner AGC threshold
24
Delayed tuner AGC output
TDA 5940-2
Semiconductor Group
47
TDA 5940-2
Block Diagram
Semiconductor Group
48
TDA 5940-2
Absolute Maximum Ratings
T
A
= 0 to 85 C
Parameter
Symbol
Limit Values
Unit
min.
max.
Supply voltage
V
S
13.2
V
Junction temperature
T
j
150
C
Storage temperature
T
stg
125
C
Thermal resistance
R
th JA
70
K/W
Operating Range
Supply voltage
V
S
7.5
13.2
V
Supply voltage delayed tuner AGC
V
1
1
10
V
Ambient temperature during operation
T
A
0
85
C
Input frequency range
f
IF
12
80
MHz
Semiconductor Group
49
TDA 5940-2
Characteristics
T
A
= 0 to 85 C;
V
S
= 12 V
Parameter
Symbol
Limit Values
Unit
Test Condition
min.
typ.
max.
Total current
I
19
46
mA
SCART Switch
H/open = SCART = Pb
L = RF
V
21
V
21
2
0
5
1.5
V
V
Volume Control Voltage
Minimal volume
Maximal volume
V
8
V
8
0
3.6
5
V
V
MUTE Voltage
H/open = AF ON
L = AF MUTE
V
15
V
15
2
0
5
1.5
V
V
Dynamic Parameter
Video IF Section
IF-input sensitivity
V
1/2
70
100
V
V
Video
3 dB
Max. IF-input voltage
V
1/2
100
140
mV
V
Video
+ 3 dB
IF-control range
V
IF
66
dB
Video demodulator
output voltage
V
11pp
1.35
1.5
1.65
V
V
IF IN
= 10 mV
Gain of SCART Switch
SCART/Video output
Video/SCART output
Video/Video output
G
16-17
G
12-18
G
12-17
2
1
2
Cross talk attenuation
a
50
dB
f
IN
= 0 ... 5 MHz
Semiconductor Group
50
TDA 5940-2
Characteristics (cont'd)
Alignment Instructions
At a video carrier input level of
V
1/2
= 4 mVrms,
f
PC
= 38.9 MHz, and a superimposed AGC voltage
of
V
22
= 1.5 V, the demodulator tank circuit is preliminarily aligned until a max. video signal
V
11pp
is
obtained at the video output. Any suitable video test signal can be used for modulation. The AGC
voltage
V
22
is reduced until the signal is approx. 1 Vpp and the max. video signal is obtained when
fine-aligning the demodulator tank circuit. The alignment is not critical due to relatively large
bandwidth of the demodulator tank circuit. Fine-tuning to intercarrier
S
/
N
, differential phase or
2T-pulse characteristics is possible.
Parameter
Symbol
Limit Values
Unit
Test Condition
min.
typ.
max.
Sound IF Section
Min. sound IF-input voltage
(min. control)
V
9
70
V
AF-output voltage
V
6
500
mV
f
= 30 kHz
f
mod
= 1 kHz
F
SIF
= 5.5 MHz
SCART AF-output voltage
V
5
500
mV
f
= 30 kHz
f
mod
= 1 kHz
F
SIF
= 5.5 MHz
Total harmonic distortion
THD
AFo
0.5
%
f
= 30 kHz
f
mod
= 1 kHz
F
SIF
= 5.5 MHz
Max. SCART-input voltage
V
7RMS
2
V
Gain SCART-sound switch
G
7-6
1
V
8
3.6 V
Semiconductor Group
51
TDA 5940-2
Test Circuit
Semiconductor Group
52
TDA 5940-2
Application Circuit
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