Methods and apparatus for adaptive timing for zero voltage transition power converters

A method, comprising:

• executing a plurality of cycles for a power converter, each cycle including:
• turning on a first switch during a first period, the first switch having a first current handling terminal coupled to a first terminal of a power supply and a second current handling terminal coupled to a switch node coupled to a terminal of a first inductor, the first inductor having another terminal coupled to a first terminal for supplying a current output to a load;
• turning on a second switch during a second period, the second period occurring after the first period such that the first switch and second switch are not turned on simultaneously, the second switch having a first current handling terminal coupled to the switch node and a second current handling terminal coupled to a second terminal of the power supply;
• turning on a third switch at a first time during the second period and turning the third switch off at a second time after the second period but before a beginning of the first period of a succeeding cycle, a first current handling terminal of the third switch coupled to the first terminal of the power supply and a second current handling terminal coupled to an auxiliary node and to a first terminal of a second inductor, a second terminal of the second inductor coupled to the switch node;
• turning on a fourth switch at a third time after the second time and turning the fourth switch off during the first period of the succeeding cycle, the fourth switch having a first current handling terminal coupled to the auxiliary node and a second current handling terminal coupled to the second terminal of the power supply;
• and
• turning on a fifth switch during a third period at an end of the first period if the voltage on the first terminal of the second inductor is high after the second period, the fifth switch having a first current handling terminal coupled to the auxiliary node and a second current handling terminal coupled to the switch node.

An integrated circuit for controlling a switched power converter, comprising:

• a first switch control output;
• a second switch control output;
• a third switch control output;
• a fourth switch control output;
• a fifth switch control output;
• a switch node voltage input;
• an auxiliary switch node voltage input;
• and
• timing circuitry, configured:
• to cause a first closed signal on the third switch control output before a first open signal on the second switch control output;
• to cause the third switch control output to provide a second open signal after a first selected time after the first open signal, to cause the fourth switch control output to provide a third closed signal a second selected time after the second open signal and third open signal a third selected time after the third closed signal, and to cause the first switch control output to provide a fourth closed signal after the second open signal and a fourth open signal after the third open signal, the timing circuitry configured to detect if a high voltage is on the auxiliary switch node voltage input after the third open signal and to provide a fifth closed signal on the fifth switch control output during a transition from the fourth closed signal to the fourth open signal responsive to the detecting.