INTEGRATED CIRCUITS FOR TV AND RADIO RECEIVERS TDA1701 Sound Channel IC for TV Receivers (18-Pin Plastic Package with 2 Cooling Fins) The TDA1701 is a bipolar integrated circuit containing all stages re- quired in the sound channel of a TV receiver. It is suitable for mains as well as battery-operated receivers. The cooling tabs projecting from the case on either side are sufficiently large for a 2 W output power without additional heat sink facilities. If these tabs are cooled further, for example by being soldered to a sufficiently large copper-clad area of the printed circuit board, an output power up to 4 W is permissible. As can be seen from the Figures, the TDA1701 requires only few ex- ternal components. It consists of a limiting IF amplifier, a coincidence demodulator, a circuit for electronic volume adjustment and a com- plete AF amplifier with preamplifier, driver and output stage in series push-pull connection. The IF section has excellent limiting properties and operates with high AM suppression. The coincidence demodula~ tor supplies a low-distortion AF signal. For connection to a video recorder, the TDA1701 is provided with a direct demodulator output which is not affected by the electronic volume control. In order to receive signals from the AF output of a video recorder or from other AF signal sources, the TDA1701 is provided with an AF in- put which can be influenced by the electronic volume control. A switching voltage allows the IF section to be switched off. The output amplifier is protected against overheating. At a chip temperature of approximately 150 C the AF voltage at the driver transistor is short- circuited. -| fy AF VCR Bk 15k 10k H Z i }-----__0 - +--+ 424 IF 3 6 10 geMiz = (TDA 1701-~|~- ----|----~--- --4 c | | Stabilizing Overload l 3p circuit protection H 3 | | Electronic th AF | amplifier Demodutator F] volume amplifi t 00p | control . I , ! 3p 2 l LL fee ee ake 27k a n o4 &70 uF + IF] turn-off a c On s 16 at { 212 woul" [ean TDA1701 Application Circuit a b 20k 200 T 1004 c a) Circuitry between terminals a, b and c of the circuit above a) without tone control network, with linear frequency response b) with tone control network TDA1236 Sound Channel IC for TV Receivers (18-Pin Plastic Package) Bipolar integrated circuit for the sound channel of TV receivers. The device comprises a symmetrical IF amplifier with excellent limiting properties, a symmetrical coincidence demodulator, a volume control circuit featuring Fletcher-Munson characteristics, bass and treble control, and an impedance converter output stage for directly driving a power amplifier. The volume control, bass and treble control circuits are d.c. driven, so that only simple linear potentiometers are needed, providing an extre- mely simple circuit design. Only few external components are needed. When used with a video recorder, the IF amplifier can be rendered in- operative electronically and the AF connection for the VCR can be switched over from record to playback. AF VER 15 42V TIA I236 - | +6V stab, 15k sk | ] symmetrical Prskl- | trette | Bass | Volume Control Conteal } Control | Contral 5) 109 9d86 O7 ots di }12 413 _ Bn BI sh To1s al + + + R Bn _]220 lok 10k 10k TDA1236 Block Diagram and Application Circuit 32