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20W audio amplifier using TDA7240 Schematic Circuit Diagram


The audio amplifier depicted in this diagram utilizes the TDA7240 integrated circuit, manufactured by ST Microelectronics. The TDA7240 is a compact audio amplifier IC capable of supplying 20 watts of audio output power to a 4-ohm load. It offers the advantage of requiring a minimal number of external components and is conveniently available in a 7-pin compact Heptawatt package. Additionally, the IC incorporates several beneficial features, including loudspeaker protection, short circuit protection, low noise levels, low distortion, and more. The circuit can be powered by a single 12V DC supply, rendering it particularly well-suited for use in car audio applications.

Circuit diagram

20W audio amplifier using TDA7240 Schematic Circuit Diagram


  • Assemble the circuit on a good quality PCB.
  • Use 12V DC for powering the circuit.
  • K1 can be a 4 ohm, 20W speaker.
  • S1 is the standby switch and S2 is the ON/OFF switch.
  • LED D2 is a power-ON indicator.
  • Fit the IC to a proper heatsink.

About TDA7240A:

Designed especially for car radios, the TDA7240A is a bridge audio amplifier IC capable of delivering 20 watts of power. Its minimal external component requirement and compact Heptawatt 7-pin power package contribute to its space-efficient integration on printed circuit boards.

The TDA7240A is equipped with a comprehensive set of on-chip protective measures, ensuring reliable performance. These safeguards encompass protection against both AC and DC output short circuits (whether to ground or across the load), defense against load dump transients, and prevention of junction overheating. In the event of a short circuit to ground on one of the outputs, the TDA7240A also ensures the safety of the loudspeaker.


There are various usages of audio amplifiers. Some of them are listed as follows:

  1. In sound systems, these amplifiers are the most widely used.
  2. In various instruments that relate to music, these amplifiers are installed.
  3. In radio signal broadcasting these amplifiers are used.
  4. The signal transmission for long-distance communication is the most amplifier that is utilized.
  5. For the wireless transmission of the signals, audio amplification is required.
  6. Classification of the amplifier can be done in 3 different ways. Voltage amplifiers. Current amplifiers. Power amplifiers.

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