Siemens TBA121-5 Datasheet

FM-Sound IF with SCART Switch
and Volume Control

Features

● Outstanding limiting qualities

● Few external components

● Integrated de-emphasis resistor

● Low harmonic distortion factor

P-DIP-16

Type Ordering Code Package

TBA 121-5

Bipolar IC

TBA 121-5 Q67000-A5137 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 SCART­recording / playback function as well as an analog volume control with AF output.

Semiconductor Group 91 06.94

TBA 121-5

Pin Functions
Pin No. Function

1 Ground
2 Limiter amplifier operating point feedback

(RF decoupling of IF amplifier with appropriate capacitors is required!)

3 Limiter amplifier operating point feedback and low end

(RF decoupling of IF amplifier with appropriate capacitors is required!)
4 IF-amplifier output (emitter follower)
5 IF-amplifier output (emitter follower)
6 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)
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)
8 Connection for de-emphasis capacitor (a series resistor of 11 kΩ is integrated)
9 AF output of the SCART interface (emitter follower with short circuit limiter)
10 AF input 1 of the SCART interface (IF branch)
11 Rec/Pb switch input
12 AF input 2 of the SCART interface (SCART input)
13 Volume control
14 IF output (emitter follower)
15 +
16 IF input (limiter amplifier input; internal resistor between pin 16 and 3 typ. 800 Ω)

V

supply voltage

S

Semiconductor Group 92

TBA 121-5

Expanded Block Diagram, Part 1

Semiconductor Group 93