| 主权项 |
1. An over-current protection circuit, adapted for a pulse width modulator, the pulse width modulator comprising a trigger, a high-side switch, a low-side switch, a driving module and a control element, the trigger receiving a clock signal and according to the clock signal generating a set signal to the control element periodically, and the high-side switch connected electrically to the low-side switch, the driving module controlling the high-side switch and the low-side switch according to the set signal and a reset signal periodically to adjust an inductive current flowing through the high-side switch and the low-side switch, the control element turning on the high-side switch by at least one minimum on time, and after the minimum on time the driving module detecting whether the inductive current flowing through the high-side switch is larger than an overcurrent level, and generating an overcurrent signal when the inductive current is detected larger than the overcurrent level, the over-current protection circuit comprising:
a first pulse generator, receiving the clock signal to generate a judging signal periodically, and a judging time of the judging signal being larger than the minimum on time; a counting unit, receiving the judging signal; and an overcurrent judging unit, receiving the judging signal and the overcurrent signal to control whether the trigger outputs the set signal, wherein when the overcurrent judging unit judges the inductive current to be overcurrent according to the judging signal and the overcurrent signal, the overcurrent judging unit stops the trigger outputting the set signal to the driving module, and the counting unit counts for a predefined time according to the judging signal, and the overcurrent judging unit permits the trigger to output the set signal to the driving module periodically after the counting unit finishes counting for the predefined time. |
