The circuit diagram shown here is of a 2 x 60 Watt stereo amplifier based on the LM4780 from National Semiconductors. LM4780 is a superb audio amplifier IC capable of delivering 60W Rms power output/channel into 8-ohm speakers. The LM4780 has very low total harmonic distortion (less than 0.5% at full output) and has a power supply rejection ratio (PSRR) of 85 dB. The IC requires very few external components and has a built-in mute facility. The LM4780 is completely protected using their trademark SPiKe technology and has a signal-to-noise ratio greater than 97dB. The circuit given here is well suitable for applications like components stereos, self-powered speakers, home theatre systems, compact stereos, etc.
A 60-90W High-Quality power amplifier design is offered here to commemorate the hundredth design released to this website and to satisfy the requests of many correspondents who wanted an amplifier with more power than the 25W MOSFET. The circuit topology is similar to that of the previous amplifier, but the output pair is made up of the very tough IRFP240 and IRFP9240 MOSFET devices, while the preceding stages are made up of well-known high-voltage Motorola transistors.
LM4780 pin configuration
- The circuit must be assembled on a good quality PCB.
- The amplifier can be powered using a 35V DC dual supply.
- K1 and K2 must be 8 ohms and 60W speakers.
- An adequately sized heat sink must be fitted to the IC.