SPEAKER PROTECTION CIRCUIT FOR BTL POWER AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide a speaker protection circuit that protects a speaker by detecting a DC abnormal voltage of an input signal in a balanced transformerless BTL power amplifier so as to automatically turn off an output. SOLUTION: This protection circuit consists of a clip detection circuit 1 that detects clips which exceed the saturation level of an output voltage waveform Vout, due to saturation of a BTL power amplifier 30 to provide an output of a clip detection signal Scp, a timer circuit 4 that receives the clip detection signal Scp of the clip detection circuit 1 to provide an output, when a clip CP is consecutive for a prescribed time Toff or longer, and a control circuit 5 that controls an output on/off circuit 3 that receives an output of the timer circuit 4 to turn off the output Vout of the BTL power amplifier 30.