Self-recovering over current protection circuit for class-D audio power amplifier

To avoid to be damaged when class D power amplifier chip load is short circuit, the paper presents a self-recovering over current protection circuit in chip. The over current protection circuit would active used to shut down the output buffer when two output pins short-circuit to power supply, short-circuit to ground or short-circuit to each other. Different from previously reported scheme, the scheme could help chip to recover normal work automatically after short circuit removes. Chip achieves a maxim power of 2.75W and maxim efficiency of 90% at a 4Ohm load when power supply voltage is 5V. Chip operates with a 2.5V to 5.5V supply voltage, 0.35μm, double poly, triple metal BiCMOS process. It has an area of 1.5 × 1.5 mm² and it achieves a THD as low as 0.1%, with a flat band response between 20 Hz and 20 KHz. The over current threshold is about 3A.