Patent ID: 8472217

Claim:
A switching mode power supply, comprising: a transformer having a primary winding and a secondary winding to supply power to a load; a feedback circuit that generates a feedback signal that varies in relation to the load on the secondary winding; a switching circuit coupled to the primary winding to control current flow through the primary winding; a frequency control circuit that controls a switching frequency of the switching circuit based on the feedback signal; a current limiting circuit that limits current flow through the primary winding by causing the switching circuit to suspend current flow through the primary winding when the current reaches a peak current limit that is set based on the feedback signal; a burst mode control circuit that bypasses the frequency control circuit and the current limiting circuit to control operation of the switching circuit when the load on the secondary winding falls below a minimum load threshold; and wherein the switching mode power supply operates in three modes: a first mode during which the switching frequency varies as a function of the feedback signal and the peak current limit is constant; a second mode during which both the switching frequency and the peak current limit vary as a function of the feedback signal; and a burst mode during which operation of the frequency control circuit and the current limiting circuit is suspended.