METHODS AND POWER CONTROLLERS FOR PRIMARY SIDE CONTROL

摘要

Power controllers and related primary-side control methods are disclosed. A disclosed power controller has a comparator and an ON-triggering controller. The comparator compares a feedback voltage with an over-shot reference voltage. Based on an inductance-coupling effect, the feedback voltage represents a secondary-side voltage of a secondary winding. Coupled to the comparator, the ON-triggering controller operates a power switch at about a first switching frequency when the feedback voltage is lower than the over-shot reference voltage. The ON-triggering controller operates the power switch at about a second switching frequency when the feedback voltage exceeds the over-shot reference voltage. The second switching frequency is less than the first switching frequency.

主权项

1. A primary-side control method comprising:
providing a feedback node, coupled to an auxiliary winding; generating a feedback voltage by sampling the feedback node during discharging of the secondary winding; controlling a power switch in a first switching frequency; comparing the feedback voltage and an over-shot reference voltage; and controlling the power switch in a second switching frequency when the feedback voltage is greater than the over-shot reference voltage; wherein the second switching frequency is lower than the first switching frequency, and the feedback voltage represents a secondary-side voltage of the secondary winding through an inductance-coupling effect.