METHOD TO CONTROL A MINIMUM PULSEWIDTH IN A SWITCH MODE POWER SUPPLY

摘要

A power converter circuit includes a transformer and a main switch controller by a primary side controller. A sensing circuit is implemented that senses the voltage at an auxiliary winding of the transformer while the main switch is ON. The auxiliary winding is another winding on the primary side of the transformer, magnetically coupled to the secondary winding and electrically isolated from the primary winding. When the voltage across the auxiliary winding reaches a predefined threshold voltage level, the main switch is switched OFF. The threshold voltage level is set at a value that minimizes an amount of energy transferred per pulse to the secondary side of the circuit while maintaining a minimum amount of energy transfer to enable output voltage sensing at the auxiliary winding.