Controller device with adaptive synchronous rectification

A controller device for a resonant converter, the controller device comprising processing circuitry configured to:

• output a first switching signal and a second switching signal to a switching module, the switching module being configured to electrically couple a primary side winding of a transformer to a voltage source during an activated state of the first switching signal and to electrically couple the primary side winding of the transformer to a reference node during an activated state of the second switching signal;
• receive an indication of a current at the primary side winding;
• determine, using the indication of the current at the primary side winding, a first synchronous rectification signal and a second synchronous rectification signal for activating a synchronous rectification module, the synchronous rectification module being configured to generate a first channel for current to flow from a first secondary side winding of the transformer to a load during an activated state of the first synchronous rectification signal and to generate a second channel for current to flow from a second secondary side winding of the transformer to the load during an activated state of the second synchronous rectification signal,
• wherein, to determine the first synchronous rectification signal and the second synchronous rectification signal, the processing circuitry is configured to:
• determine a maximum gate on-time for the synchronous rectification module using the indication of the current at the primary side winding;
• and
• generate the first synchronous rectification signal and the second synchronous rectification signal such that an operation time of the activated state of the first synchronous rectification signal is less than the maximum gate on-time and such that an operation time of the activated state of the second synchronous rectification signal is less than the maximum gate on-time, and
• wherein, to determine the maximum gate on-time for the synchronous rectification module, the processing circuitry is configured to:
• determine, when the current at the primary side winding reduces, the maximum gate on-time to correspond to a first predetermined value when the current at the primary side winding is less than a first threshold;
• determine, when the current at the primary side winding increases, the maximum gate on-time to correspond to a second predetermined value when the current at the primary side winding is greater than a second threshold, the second threshold being greater than the first threshold;
• determine, when the current at the primary side winding reduces, the maximum gate on-time to correspond to the second predetermined value when the current at the primary side winding is less than a third threshold, the third threshold being greater than the second threshold;
• and
• determine, when the current at the primary side winding increases, the maximum gate on-time to correspond to the first predetermined value when the current at the primary side winding is greater than a fourth threshold, the fourth threshold being greater than the third threshold;
• and
• output the first synchronous rectification signal and second synchronous rectification signal to the synchronous rectification module.

A controller device for a resonant converter, the controller device comprising processing circuitry configured to:

• output a first switching signal and a second switching signal to a switching module, the switching module being configured to electrically couple a primary side winding of a first transformer to a first voltage source during an activated state of the first switching signal and to electrically couple the primary side winding of the first transformer to a reference node during an activated state of the second switching signal;
• receive an indication of a current at the primary side winding of the first transformer;
• determine, using the indication of the current at the primary side winding of the first transformer, a first synchronous rectification signal and a second synchronous rectification signal for activating a synchronous rectification module, the synchronous rectification module being configured to generate a first channel for current to flow from a first secondary side winding of the first transformer to a load during an activated state of the first synchronous rectification signal and to generate a second channel for current to flow from a second secondary side winding of the first transformer to the load during an activated state of the second synchronous rectification signal;
• and
• output the first synchronous rectification signal and second synchronous rectification signal to the synchronous rectification module, wherein, to output the first synchronous rectification signal and the second synchronous rectification signal, the processing circuitry is configured to:
• output a high side control signal to a first high side switching element and a second high side switching element to couple a first node of a primary side winding of a second transformer to a second voltage source or the reference node;
• and
• output a low side control signal to a first low side switching element and a second low side switching element to couple, via a capacitor, a second node of the primary side winding of the second transformer to the second voltage source or the reference node,
• wherein a driver module is coupled to a secondary side winding of the second transformer and wherein the driver module activates the synchronous rectification module using a signal at the secondary side winding of the second transformer.

A method for voltage regulation comprising:

• outputting a first switching signal and a second switching signal to a switching module, the switching module being configured to electrically couple a primary side winding of a transformer to a voltage source during an activated state of the first switching signal and to electrically couple the primary side winding of the transformer to a reference node during an activated state of the second switching signal;
• receiving an indication of a current at the primary side winding;
• determining, using the indication of the current at the primary side winding, a first synchronous rectification signal and a second synchronous rectification signal for activating a synchronous rectification module, the synchronous rectification module being configured to generate a first channel for current to flow from a first secondary side winding of the transformer to a load during an activated state of the first synchronous rectification signal and to generate a second channel for current to flow from a second secondary side winding of the transformer to the load during an activated state of the second synchronous rectification signal,
• wherein determining the first synchronous rectification signal and second synchronous rectification signal comprises:
• determining a gate turn-on delay using the indication of the current at the primary side winding, wherein an edge of the first synchronous rectification signal that activates the activated state of the first synchronous rectification signal is delayed from an edge of the first switching signal that activates the activated state of the first switching signal by the gate turn-on delay and wherein an edge of the second synchronous rectification signal that activates the activated state of the second synchronous rectification signal is delayed from an edge of the second switching signal that activates the activated state of the second switching signal by the gate turn-on delay, and
• wherein determining the gate turn-on delay comprises:
• determining the gate turn-on delay to correspond to a predetermined delay when the current at the primary side winding is less than a first threshold;
• determining the gate turn-on delay to correspond to zero when the current at the primary side winding is greater than a second threshold, the second threshold being greater than the first threshold;
• and
• determining the gate turn-on delay to correspond to a portion of the predetermined delay when the current at the primary side winding is greater than the first threshold and less than the second threshold;
• and
• outputting the first synchronous rectification signal and second synchronous rectification signal to the synchronous rectification module.

A method for voltage regulation comprising:

• outputting a first switching signal and a second switching signal to a switching module, the switching module being configured to electrically couple a primary side winding of a transformer to a voltage source during an activated state of the first switching signal and to electrically couple the primary side winding of the transformer to a reference node during an activated state of the second switching signal;
• receiving an indication of a current at the primary side winding;
• determining, using the indication of the current at the primary side winding, a first synchronous rectification signal and a second synchronous rectification signal for activating a synchronous rectification module, the synchronous rectification module being configured to generate a first channel for current to flow from a first secondary side winding of the transformer to a load during an activated state of the first synchronous rectification signal and to generate a second channel for current to flow from a second secondary side winding of the transformer to the load during an activated state of the second synchronous rectification signal,
• wherein determining the first synchronous rectification signal and the second synchronous rectification signal comprises:
• determining a maximum gate on-time for the synchronous rectification module using the indication of the current at the primary side winding;
• and
• generating the first synchronous rectification signal and the second synchronous rectification signal such that an operation time of the activated state of the first synchronous rectification signal is less than the maximum gate on-time and such that an operation time of the activated state of the second synchronous rectification signal is less than the maximum gate on-time, and
• wherein determining the maximum gate on-time comprises:
• determining, when the current at the primary side winding reduces, the maximum gate on-time to correspond to a first predetermined value when the current at the primary side winding is less than a first threshold;
• determining, when the current at the primary side winding increases, the maximum gate on-time to correspond to a second predetermined value when the current at the primary side winding is greater than a second threshold, the second threshold being greater than the first threshold;
• determining, when the current at the primary side winding reduces, the maximum gate on-time to correspond to the second predetermined value when the current at the primary side winding is less than a third threshold, the third threshold being greater than the second threshold;
• and
• determining, when the current at the primary side winding increases, the maximum gate on-time to correspond to the first predetermined value when the current at the primary side winding is greater than a fourth threshold, the fourth threshold being greater than the third threshold;
• and
• outputting the first synchronous rectification signal and second synchronous rectification signal to the synchronous rectification module.