A technique for extending the operating range of a flyforward converter to low input voltages. In one aspect, power converter includes a positive input supply rail and a negative input supply rail. A power converter input voltage is to be applied between the positive and negative input supply rails. A flyback energy transfer element having a flyback input winding and a forward energy transfer element having a forward input winding are also included. The flyback and forward input windings are coupled between the positive and negative input supply rails. Voltage control circuitry coupled to the forward energy transfer element is also included to reduce a voltage across the forward input winding, substantially to zero, when the power converter input voltage falls below a first threshold value.
Techniques are disclosed to regulate the output power of a power supply. An example regulator circuit includes a feedback circuit coupled to generate a feedback signal in response to an output of a power supply. The feedback circuit includes a voltage regulation circuit, a current regulation circuit and a transition region regulation circuit coupled to sense the output of the power supply and generate first, second and third regulation signals, respectively. The feedback signal is responsive to the first, second and third regulation signals. A switch coupled to an energy transfer element coupled between an input and the output of the power supply. A controller is coupled to the switch to control switching of the switch to regulate the output of the power supply in response to the feedback signal.
