FM-Sound IF with SCART Switch
and Volume Control
TBA 121-5
Bipolar IC
Features
q
q
q
q
Outstanding limiting qualities
Few external components
Integrated de-emphasis resistor
Low harmonic distortion factor
P-DIP-16
Type
TBA 121-5
Ordering Code
Q67000-A5137
Package
P-DIP-16
Functional Description
FM-IF amplifier, consisting in a limiter amplifier with FM demodulator. The AF section contains a
SCART-record/playback switch as well as AF output with volume control. The control of the volume
is controlled via an analog control input, and the SCART switch is controlled via a switch input.
Application
Application of the IC is intended in mono TV sets.
Circuit Description
In its FM section, the component contains an eight stage, symmetrical limiter amplifier with
subsequent coincidence demodulator. The AF section contains an analog switch for the SCART-
recording / playback function as well as an analog volume control with AF output.
Semiconductor Group
91
06.94
TBA 121-5
Pin Functions
Pin No.
1
2
3
4
5
6
Function
Ground
Limiter amplifier operating point feedback
(RF decoupling of IF amplifier with appropriate capacitors is required!)
Limiter amplifier operating point feedback and low end
(RF decoupling of IF amplifier with appropriate capacitors is required!)
IF-amplifier output (emitter follower)
IF-amplifier output (emitter follower)
Demodulator input with high impedance input and internal 15 kΩ supply resistor
(if an
LC
circuit is used, the
Q
is determined by the damping resistance across
pins 6 and 7)
Demodulator input with high impedance input and internal 15 kΩ supply resistor
(if an
LC
circuit is used, the
Q
is determined by the damping resistance across
pins 6 and 7)
Connection for de-emphasis capacitor (a series resistor of 11 kΩ is integrated)
AF output of the SCART interface (emitter follower with short circuit limiter)
AF input 1 of the SCART interface (IF branch)
Rec/Pb switch input
AF input 2 of the SCART interface (SCART input)
Volume control
IF output (emitter follower)
+
V
S
supply voltage
IF input (limiter amplifier input; internal resistor between pin 16 and 3 typ. 800
Ω)
7
8
9
10
11
12
13
14
15
16
Semiconductor Group
92