Power Supply with Tickle Pulse Injection

摘要

A power supply injects a series of “tickle” pulses into a pulse width modulated (PWM) controller to induce the controller to generate PWM pulses at a minimum switching frequency, preferably one that is super-sonic (especially for audio applications). The switching frequency may also be selected or controlled such that it avoids resonances in the power supply. The “tickle” pulses may be clocked by the same clock that times the PWM controller, and they may be shaped to help ensure that the power supply maintains some regulation during low-load conditions.

主权项

1. A power supply comprising:
an output node that is configured to deliver a target output voltage to a variable load; one or more power switches that controls power delivered to the output node; a controller configured to produce a series of variable width pulses that control operation of the power switches such that the output node delivers a near constant target output voltage to the load, wherein the controller is configured to receive a voltage error signal indicating the difference between an actual voltage at the load and the target voltage and alter at least the width of the pulses delivered to the power switches, and wherein the controller is configured to operate in a pulse skipping mode, where periods of switching and no switching are controlled by a hysteretic window of the voltage error signal; and a tickle pulse generator configured to generate a series of tickle pulses that are combined with the voltage error signal supplied to the controller, wherein at least some of the pulses cause the controller to generate a pulse delivered to the power switches when the load draws little or no power.