Load current compensation in synchronous power converters

A load current compensation circuit for a synchronous power converter, comprising:

• at least one comparator having a first input coupled to a phase node between upper and lower power switches of a synchronous power converter and a second input configured at a zero level, the at least one comparator operable to compare a voltage level at the phase node with the zero reference level;
• and
• a reference voltage adjustment module, coupled to an output of the at least one comparator for processing signals from the at least one comparator, the reference voltage adjustment module operable to
• receive an indication of load current levels of a synchronous power converter from a mode select signal, and
• provide a control signal to control a gate driver for at least one of the power switches in a light load current condition as the voltage level at the phase node increases from the zero reference level during a zero threshold crossing point of inductor current for the synchronous power converter;
• wherein, when a body diode of the at least one power switch continues to conduct after the gate driver for the at least one power switch is turned off, the reference voltage adjustment module is operable to incrementally adjust a reference voltage level for the at least one power switch until the body diode conduction of the at least one power switch is no longer conducting.

A voltage regulation system, comprising:

• a voltage output circuit having upper and lower power switches, the voltage output circuit operable to provide a voltage output of a phase node coupled between the upper and lower power switches;
• a low power signal module operable for detecting a mode select signal from a variable load element powered by the voltage output;
• a load current compensation circuit coupled to the voltage output circuit and the low power signal module, the load current compensation circuit including,
• at least one comparator in operative communication with the low power signal module, the at least one comparator operable to compare the voltage output of the phase node with a zero reference level, and
• a reference voltage adjustment module operable to receive an output of the at least one comparator, the reference voltage adjustment module configured to provide a control signal, based on the output of the at least one comparator, to turn off at least one of the lower power switch and the upper power switch when the variable load element indicates a light load condition and the voltage output of the phase node is increasing from the zero reference level at a zero threshold crossing of negative inductor current for the voltage output circuit;
• and
• a controller operable to provide a control input to the voltage output circuit based at least in part on a feedback signal from the voltage output circuit;
• wherein the load current compensation circuit provides load current compensation for the system based on a detected body diode conduction of at least one of the upper and lower power switches by incrementally adjusting a reference voltage level whereby the load current compensation stops after a predetermined number of operating cycles for the control input to the voltage output circuit.

An electronic system, comprising:

• a varying load device having at least one power input;
• and
• a power converter having at least one output coupled to the at least one power input of the varying load device, the power converter including,
• a load current compensation circuit coupled to the power converter, the load current compensation circuit configured to correct a reference voltage for at least one power switch of the power converter based on an indication of a light load condition from the varying load device;
• wherein the load current compensation circuit compensates for load currents experienced by the power converter by adjusting the reference voltage for the at least one power switch when the at least one power switch is turned off based at least in part on a body diode conduction level associated with the at least one power switch after the at least one power switch is turned off, and
• wherein the load current compensation circuit stops the load current compensation once the body diode is no longer conducting.