68W power audio amplifier circuit based on IC LM3886

This is a 68W power audio amplifier circuit based on National Semiconductor's monolithic ICLM3886. The LM3886 is intended for single channel operation. Bipolar/split/symmetric power supply used to operate this amplifier circuit.

The LM3886 is a high-performance audio power amplifier capable of delivering 68W of continuous average power into a 4ohm load and 38W of 8ohm power at 0.1% THD+N over the 20Hz-20kHz range.

LM3886 amplifier specifications:

Maximum output power: 68WRMS-108W peak

Total harmonic distortion: %0.03 at 60W

Signal-to-noise ratio: 110dB at 60W - 92.5dB at 1W

PSRR: 120dB

Protection circuit: DC/AC short circuit protection and thermal protection

Output Category: Conjugate AB-A

The LM3886's performance leverages its Self-Peak Instantaneous Temperature (Ke) (SPiKe) protection circuitry, which puts it above discrete and hybrid amplifiers by providing an inherently dynamic protective Safe Operating Area (SOA). SPiKe protection means these components are fully protected at the output against overvoltage, undervoltage, overload, including supply short circuits, thermal runaway and transient temperature spikes.

The LM3886 maintains an excellent signal-to-noise ratio of greater than 92dB with a typical low noise floor of 2.0uV. It exhibits an extremely low THD+N value of 0.03% across the audio spectrum from rated output to rated load, and provides excellent linearity and an IMD (SMPTE) typical rating of 0.004%.