100W Audio Amplifier TDA7294 Schematic Circuit Diagram

The 100W Audio Amplifier TDA7294 is a dedicated, monolithic Class AB audio amplifier engineered with Hi-Fi applications in mind. This IC is equipped with a DMOS output stage, enabling it to yield an impressive 100W RMS output when connected to an 8-ohm speaker and powered by a dual supply of +/-38V.

The TDA7294 boasts commendable attributes, including low noise, minimal distortion, effective ripple rejection, and the flexibility to operate within a broad range of supply voltage levels. Moreover, it incorporates built-in safeguards, such as short circuit protection and thermal shutdown circuitry, further enhancing its reliability and durability. You’ll find the TDA7294 available in two package options: the multi-watt 15V and the multi-watt 15H formats.

Description

Within the circuit, the TDA7294 is meticulously configured to yield a substantial 100W output power when connected to an 8-ohm loudspeaker, drawing power from a +/-38V supply.

C8 assumes the role of the input coupling capacitor, channeling the input signal to the non-inverting input (Pin 3) of the IC. C3 and C9 function as power supply filter capacitors, while C10 and C4 operate as bypass capacitors. C2, on the other hand, serves as the bootstrap capacitor.

An RC network, comprising R1 and C1, plays a pivotal role in enhancing the high-frequency stability of the amplifier and serves as an effective deterrent against potential oscillations.

For fine-tuning operational aspects, R2 and C6 collaborate to determine the mute time constant, while R3 and C5 define the standby time constant. The circuit includes S1, the mute switch, and S2, the standby switch, for control purposes.

Notably, R5 sets the input resistance, with the amplifier’s input impedance being directly influenced by its value. Meanwhile, R4 and R6 combine to establish the closed-loop gain, which, based on the chosen values, amounts to 30dB. Finally, C2 acts as a feedback capacitor and also provides essential DC decoupling.

Circuit Diagram

Notes.

• The supply voltage range is +/- 10V to =/-40V DC.
• Heat sink is required and its thermal resistance should be around 0.038 degree Celsius/Watt.
• Use an 8 Ohm 150W speaker as the load.
• For 100W output the supply voltage must be +/-38VDC.
• The power supply must be well filtered and free of ripples.
• If ripples are present in the power supply it may cause oscillations.
• VM = 1.5V is the mute ON threshold and VM=3.5V is the mute OFF threshold.
• VSTBY = 1.5V is the standby on threshold and VSTBY = 3.5V is the standby OFF threshold.
• Typical input resistance of TDA7294 is 100KiloOhm.
• Frequency response is 20Hz to 20KHz.
• 145 degree Celsius is the threshold for thermal shutdown. Slew rate of TDA7294 is 10V/microsecond and the open loop voltage gain is 80 dB.
• Quiescent current of TDA7294 is approximately 30mA and its maximum value is 65mA.