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.