For load currents greater than a threshold current, the voltage regulator
operates in a conventional manner by fully turning on and off one or more
switching transistors at a duty cycle necessary to maintain the output
voltage a regulated voltage. Upon a load current below a threshold being
detected, a controller stops the switching of the transistor(s) and
applies a reduced drive signal to the high side transistor so as to apply
a constant trickle current to the load. Unnecessary components are shut
down to save power. When the output voltage falls below a threshold, the
normal switching routine is resumed to recharge the regulator's output
capacitor to a certain level, and the regulator once again enters the
light load current mode. By not completely shutting down the transistors
at light load currents, as in done in a conventional
intermittent-operation mode, there is lower power loss by less frequent
switching of the transistor(s).