Apparatus and method for reverse current correction for a switching regulator

A circuit for switching regulation, comprising:

• a first switch circuit having at least a first control input, wherein the first switch circuit is coupled to a first node;
• a synchronous switch circuit having at least a first control input, wherein the synchronous switch circuit is coupled to the first node;
• an error circuit having at least an output;
• a switch control circuit having at least an input, and an output that is coupled to the control input of the control input of the first switch circuit, wherein the switch control circuit includes a pulse modulation circuit;
• a synchronous switch enable control circuit having at least an output;
• a synchronous switch enable logic circuit having at least an output that is coupled to the control input of the synchronous switch circuit, and a first input that is coupled to the output of the switch control circuit, and a second input that is coupled to the output of the synchronous switch enable control circuit;
• a level shift circuit having at least a first input that is coupled to the output of the error circuit, and an output that is coupled to the input of the switch control circuit;
• and
• a reverse current duration detection circuit having at least an output that is coupled to the level shift circuit.

A method for regulation, comprising:

• opening and closing a first switch circuit based on a first switch control signal such that an output signal is regulated;
• opening and closing a synchronous switch circuit based on a synchronous switch control signal;
• providing the first switch control signal based, in part, on the output signal;
• providing the synchronous switch control signal such that:
• if the synchronous switch enable signal corresponds to an active level, and the first switch control signal corresponds to an inactive level:
• the synchronous switch control signal corresponds to an active level,
• else:
• the synchronous switch control signal corresponds to an inactive level;
• providing the synchronous switch enable signal such that, during a transition time interval that occurs over at least three consecutive switching cycles:
• a parameter of the synchronous switch enable signal is gradually increased such that partially synchronous rectification is performed, and such that the partially synchronous rectification gradually approaches fully synchronous rectification;
• or
• the parameter of the synchronous switch enable signal is gradually decreased such that the partially synchronous rectification is performed, and such that the partially synchronous rectification gradually approaches asynchronous rectification;
• during the transition time interval, detecting a reverse current duration, wherein the reverse current duration is the duration for which a body diode of the first switch circuit is conducting reverse current while the first switch control signal correspond to an active level;
• and
• in a subsequent switching cycle of the transition time interval, increasing a duration for which the first switch circuit is closed based on the detected reverse current duration.