Efficient negative-sense detection of synchronous recitifer in voltage converter

A flyback converter system, the system comprising:

• a flyback transformer;
• a synchronous rectifier (SR) coupled to a secondary side of the flyback transformer;
• and
• a secondary side controller coupled to the secondary side of the flyback transformer and the SR, the secondary side controller comprising:
• an analog-to-digital converter (ADC) coupled to a voltage bus (VBUS), the ADC to output a digital value corresponding to a voltage level of the VBUS;
• first logic coupled to the ADC, the first logic configured to generate a reference voltage based on the digital value;
• second logic configured to generate a VBUS gain value based on output power of the flyback transformer;
• an integrator to accumulate current corresponding to a sensed voltage at a drain of the SR, the accumulated current to be modified according to the VBUS gain value, wherein the integrator outputs an updated sensed voltage;
• and
• a comparator to output a detection signal, indicative of a negative sense voltage detection, in response to the updated sensed voltage matching the reference voltage.

A method of operating a secondary side controller for a flyback alternating current-to-direct current (AC-DC) converter that comprises an analog-to-digital converter (ADC) coupled to a voltage bus (VBUS), first logic, second logic, an integrator, a current compensation circuit, and a comparator, wherein the method comprises:

• generating, using the ADC, a digital value corresponding to a voltage level of the VBUS;
• generating, using the first logic, a reference voltage based on the digital value;
• generating, using the second logic, a VBUS gain value based on output power of a flyback transformer of the flyback AC-DC converter;
• accumulating, by the integrator, a current corresponding to a sensed voltage at a drain of a synchronous rectifier (SR) of a secondary side of the flyback transformer;
• modifying, by the current compensation circuit, the accumulated current of the integrator based on the VBUS gain value;
• and
• outputting, by the comparator, a detection signal, indicative of a negative sense voltage detection, in response to the modified accumulated current matching the reference voltage.