Patent ID: 8576588
Filing Date: 2013-11-05
Classification: H05B

Abstract:
1. A switching mode power supply, comprising: a transformer having a primary winding, a secondary winding, and an auxiliary winding; a switching circuit coupled to the primary winding, the switching circuit having a switch coupled to the primary winding to control current flow through the primary winding; a calculator configured to receive a switching control signal and a current sense signal, wherein the current sense signal represents a current flow through the primary winding, and wherein based on the switching control signal and the current sense signal, the calculator is configured to provide an equivalent current signal; a zero-crossing detector coupled to the auxiliary winding, wherein the zero-crossing detector provides a zero detected signal when a voltage across the auxiliary winding first crosses zero; and a controller configured to receive the equivalent current signal, the zero detected signal, the current sense signal, and a reference signal, and to provide the switching control signal to the switching circuit based thereon.