Patent attributes
This invention generally relates to synchronous rectifier controllers for an SMPS. One controller comprises: a sensor to sense a signal on a secondary side, to detect turn off of the switch; a charge source to, in response to a said detection, charge a control terminal of the rectifier to a voltage beyond a threshold voltage of the synchronous rectifier to allow the synchronous rectifier to conduct current of the secondary winding; and a linear amplifier having an output to sink current from the control terminal dependent on a difference between a voltage across the synchronous rectifier and an amplifier reference value, said voltage across the synchronous rectifier being a voltage across a controllable conduction path for current of the secondary winding, the linear amplifier to inhibit discharge of the control terminal from the voltage beyond the threshold voltage until the voltage across the synchronous rectifier reaches the amplifier reference value.
