Compensation sample and hold for voltage regulator amplifier
AssigneeIntersil Americas Inc.
InventorsPaul K. Sferrazza, Stanley F. Wietecha
Life of this patent
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Abstract
The problem of charge leakage in the AC compensation filter for the error amplifier of a pulse width modulation (PWM)-based DC—DC converter is effectively obviated by controllably sampling and storing the voltage across the AC compensation filter, in response to a transition of the operation of a DC power supply from run or active mode to quiescent or sleep mode. The sampled voltage is retained as a compensation voltage throughout the quiescent mode, so that it will be immediately available to the PWM circuitry at the termination of the quiescent interval. This serves to ensure a relatively smooth (low noise) power supply switch-over during a subsequent transition from quiescent to active mode.
Claims15
A method for effecting a relatively smooth power supply switch-over during a transition from quiescent to active mode of operation of a DC—DC converter comprising the steps of:
- (a) in response to a transition in the operation of said DC—DC converter from run mode to quiescent mode, sampling and storing the voltage of an AC compensation filter as a compensation voltage for an error amplifier for said DC—DC converter;
- and
- (b) in response to a transition in the operation of said DC—DC converter from quiescent mode to run mode, coupling said compensation voltage to drive circuitry of said DC—DC converter.
An apparatus effecting a relatively smooth power supply switch-over during a transition from quiescent to active mode of operation of a DC—DC converter comprising:
- a sample and hold circuit, which is operative, in response to a transition in the operation of said DC—DC converter from run mode to quiescent mode, to sample and store the voltage of an AC compensation filter as a compensation voltage for an error amplifier for said DC—DC converter;
- and
- a compensation voltage coupling circuit, which is operative, in response to a transition in the operation of said DC—DC converter from quiescent mode to run mode, to apply said compensation voltage to drive circuitry of said DC—DC converter.
In a DC—DC converter having an AC compensation filter coupled in circuit with an error amplifier to which a control voltage and a feedback voltage are supplied, the output of said error amplifier being coupled to drive circuitry for said DC—DC converter, the improvement comprising an arrangement for effecting a relatively smooth power supply switch-over during a transition from quiescent to active mode of operation of said DC—DC converter, by sampling and storing the voltage of an AC compensation filter as a compensation voltage for an error amplifier for said DC—DC converter, in response to a transition in the operation of said DC—DC converter from run mode to quiescent mode and, in response to a transition in the operation of said DC—DC converter from quiescent mode to run mode, coupling said compensation voltage to drive circuitry for said DC—DC converter.
Dependencies are inferred from the claim text.