The LM4781 is a three channel audio amplifier capable of typically delivering 35W per channel of continuous average output power into an 8Ω load with less than 0.5% THD+N from 20Hz - 20kHz. The LM4781 is fully protected utilizing National’s Self Peak Instantaneous Temperature (°Ke) (SPiKeTM) protection circuitry. SPiKe provides a dynamically optimized Safe Operating Area (SOA). SPiKe protection completely safeguards the LM4781’s outputs against over-voltage, under-voltage, overloads, shorts to the supplies or GND, thermal runaway and instantaneous temperature peaks. The advanced protection features of the LM4781 places it in a class above discrete and hybrid amplifiers. Each amplifier of the LM4781 has an independent smooth transition fade-in/out mute. The LM4781 can easily be configured for bridge or parallel operation for higher power and bi-amp solutions. Key Specifications j Output Power/Channel with 0.5% THD+N, 1kHz into 8Ω 35W (typ) j THD+N at 3 x 20W into 8Ω (20Hz - 20kHz) 0.2% (typ) j THD+N at 3 x 20W into 6Ω (20Hz - 20kHz) 0.3% (typ) j THD+N at 3 x 20W into 4Ω (20Hz - 20kHz) 0.5% (typ) j Mute Attenuation 110dB (typ) j PSRR 85dB (min) j Slew Rate 9V/μs (typ) Features n SPiKe Protection n Low external component count n Quiet fade-in/out mute mode n Wide supply range: 20V - 70V n Signal-to-Noise Ratio ≥ 93dB (ref. to PO = 1W) Applications n Audio amplifier for component stereo n Audio amplifier for compact stereo n Audio amplifier for self-powered speakers n Audio amplifier for high-end and HD TVs