Patent ID: 6078510
Filing Date: 2000-06-20
Classification: H02M,Y02B

Abstract:
A flyback DC--DC converter comprising:a flyback transformer for storing and transferring energy to a load, the flyback transformer comprising a primary winding and an auxiliary winding;a primary control loop including a first comparator for comparing a voltage of the auxiliary winding with a threshold;a control flip-flop device connected to the output of the first comparator;a power transistor having a conducting terminal connected to the primary winding of the flyback transformer for driving the primary winding of the flyback transformer, the power transistor being connected to the control flip-flop device for switching on the power transistor in response to the first comparator;a secondary control loop for switching off the power transistor to transfer energy stored in the transformer to the load;a second comparator for comparing the voltage on the conducting terminal of the power transistor with a reference voltage and for switching on the power transistor;a logic gate having a first input connected to an output of the second comparator and an output connected to a setting terminal of the control flip-flop device; anda delay device connected to the output of the first comparator and having an output connected to a second input of the logic gate, for ensuring, under steady state conditions, a setting of the control flip-flop device by the second comparator instead of by the first comparator.