Fairchild Semiconductor Corporation

James Holt

Jonathan Klein

Ronald J Lenk

John So

Nazzareno Rossetti

Kimble Smith

In one embodiment, in a power converter system having first and second switches connected in a half-bridge arrangement at a common node from which current flows through an inductor to a regulated output terminal, wherein the regulated output terminal is connectable to a load, wherein the first and second switches are turned on and off in cycles, a method is provided for synchronous rectification. The method includes: initiating a cycle in which the first switch is turned on; developing a timer based on the on-time of the first switch during the cycle; turning off the first switch and turning on the second switch during the cycle; and outputting a control signal to turn off the second switch when either the timer expires or a new cycle is initiated to turn on the first switch, thereby providing synchronous rectification in the power converter system.

Time-based synchronous rectification in a power converter

A circuit is provided to regulate an output voltage. The circuit includes an upper transistor connected to an input voltage from a voltage source, a lower transistor connected to the upper transistor, a pulse width modulator for generating control signals for the upper and lower transistors and a voltage protection circuit. The voltage protection circuit includes an over-voltage detector circuit powered by the regulated voltage. The voltage protection circuit can cause the lower transistor to draw sufficient current from the voltage source such that an over-voltage condition becomes abated.

Output-powered over-voltage protection circuit

A switching regulator having an active droop voltage generator that is responsive to a drain-to-source current of a current sense element within the switching regulator. A droop signal affects the duty cycle of a pulse-width modulated signal generated by control loop. The pulse width modulated signal is fed back to the input of the switching regulator to control the amount of droop. The droop voltage generator is programmable, having a selectable gain-setting resistor.

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Los Altos, CA, United States of America

James Holt