Patent ID: 9431909
Filing Date: 2016-08-30
CPC Classification: H02M,Y02B

Claim Text:
1. A synchronous rectifier controller for a switched mode power supply comprising an inductive winding and a synchronous rectifier transistor with a gate, a source and a drain, the source and drain providing a conduction channel coupled to the inductive winding, the synchronous rectifier controller comprising: an input terminal for receiving an input signal related to a voltage at the drain; an output terminal configured to provide an output signal for setting a logic state of the gate; and circuitry having a first threshold and a second threshold, the circuitry configured to: wherein the circuitry comprises a timing capacitor and is configured, in order to measure the time period, to: initiate supply of a current to the timing capacitor in response to the input signal becoming equal to or crossing the first threshold such that a timing charge is accumulated by the timing capacitor; and cease supply of the current to the timing capacitor in response to the input signal becoming equal to or crossing the second threshold.