SWITCHING REGULATOR AND CONTROL CIRCUIT AND CONTROL METHOD THEREFOR

摘要

Disclosed are a switching regulator and a control circuit and a control method therefor. In one embodiment, a switching control signal with decreasing on time is generated to control a power switch in a second mode so that audio noise can be avoided when the switching regulator operates in a light loaded or unloaded condition.

主权项

1. A control circuit for controlling a power switch in a power stage of switching regulator, comprising:
a set pulse generator configured to generate set pulses in accordance with a feedback voltage, a ripple voltage and a reference voltage, wherein said feedback voltage is obtained from an output voltage of said power stage; a reset pulse generator configured to generate reset pulses in a one to one correspondence with said set pulses, wherein in a first mode a time interval between each said reset pulse and neighboring set pulse preceding thereto is constant, and in a second mode said time intervals decreases with time; and a logic circuit configured to generate a switching control signal in accordance with said set pulses and said reset pulses, wherein said switching control signal turns on said power switch when said set pulse occurs and turns off said power switch when said reset pulse occurs.