Overcurrent protection circuit

摘要

An overcurrent protection circuit for a switching mode power supply which has a switching transformer for transforming a rectified voltage into a plurality of drive voltages and a pulse width modulation circuit for generating a pulse width modulation signal in response to a desired one of the drive voltages from the switching transformer. The overcurrent protection circuit is connected between a drive voltage output terminal of the switching transformer and a drive voltage input terminal of the pulse width modulation circuit. The overcurrent protection circuit consists of a parallel circuit composed of an inductance and a resistance. When the switching transformer is short-circuited, the overcurrent protection circuit accelerates a drop of the drive voltage which is supplied from the switching transformer to the pulse width modulation circuit. The overcurrent protection circuit rapidly cuts off an overcurrent due to a short-circuit which is caused in electric or electronic equipment containing the switching mode power supply device. Therefore, components in the equipment can be protected from the overcurrent due to a short-circuit.