Abstract: A forward converter has a primary side containing a PWM controller for controlling switching of a power switch and has a secondary side coupled to the primary side via a transformer. The secondary side includes a forward transistor and a catch transistor. A secondary side switch controller controls switching of the forward transistor and the catch transistor without communication from the primary side. The secondary side switch controller detects the rising and falling of the voltages at the ends of the secondary winding to control the switching of the forward and catch transistors. A delay locked loop (DLL) is provided in the secondary side switch controller that turns on the catch transistor when the power switch is turned off and turns off the catch transistor at a predetermined time before the power switch is turned on. A separate circuit controls the catch transistor during a discontinuous mode.

Abstract: A forward converter has a primary side containing a PWM controller for controlling switching of a power switch and has a secondary side coupled to the primary side via a transformer. The secondary side includes a forward transistor and a catch transistor. A secondary side switch controller controls switching of the forward transistor and the catch transistor without communication from the primary side. The secondary side switch controller detects the rising and falling of the voltages at the ends of the secondary winding to control the switching of the forward and catch transistors. A delay locked loop (DLL) is provided in the secondary side switch controller that turns on the catch transistor when the power switch is turned off and turns off the catch transistor at a predetermined time before the power switch is turned on. A separate circuit controls the catch transistor during a discontinuous mode.