Circuit having sample and hold feedback control and method

摘要

A drive circuit and a method for maintaining an operating state of the drive circuit. The drive circuit includes a capacitor connected to an inverting input terminal of an operational amplifier and to a terminal of a current sensitive load through a switch. The output of the operational amplifier is connected to a switching regulator which has an output terminal connected to another terminal of the current sensitive load. An energy storage element is connected to the inverting input terminal of the operational amplifier. Energy is stored in the energy storage element during a first portion of a PWM pulse which is used during a second portion of the PWM pulse to generate the error signal. A drive signal is generated from the error signal where the drive signal is used to generate a voltage that biases the current source during the second portion of the PWM pulse.