A switching regulator utilizing on/off control that reduces audio noise at light
loads by adjusting the current limit of the switching regulator. In one embodiment,
a switching regulator includes a state machine that adjusts the current limit of
the switching regulator based on a pattern of feedback signal values from the output
of the power supply for a preceding N cycles of the drive signal. The state machine
adjusts the current limit lower at light loads such that cycles are not skipped
to reduce the operating frequency of the switching regulator into the audio frequency
range until the flux density through the transformer is sufficiently low to reduce
the generation of audio noise.
