PROTECTION CIRCUIT OF BTL AMPLIFIER

PURPOSE:To prevent a BTL amplifier from being destroyed, by detecting an amplifier output voltage of each BTL amplifier section forming the BTL amplifier and comparing the output voltage. CONSTITUTION:The BTL amplifier consists of the BTL amplifier sections 5, 10 for L and R channel. The output of amplifiers 2, 3 and 7, 8 of the amplifier sections 5, 10 is given to detection circuits 17, 18 via terminals 13, 14 and 15, 16. Detection signals of each detection circuit are given to a comparison and detection circuit 19 and compared. Since no output is generated from the circuit 19 at the normal operation, no control signal is outputted from a control signal generating circuit 20 of the next stage. Further, at an abnormal operation, the circuit 19 is operated, a control signal is outputted from the circuit 20, and then the amplifier function of the sections 5, 10 is stopped. Thus, the destruction in the BTL amplifier is prevented.