National Semiconductor Corporation

Faruk J Nome

George Adrian Hariman

Jeff Lee Nilles

A synchronous buck regulator controller is provided. The regulator controller includes switch control circuitry, an unloading event detection circuit, an inductor current detection circuit, and a synchronous switch control logic circuit. In operation, the regulator controller controls a main switch and a synchronous switch to control the buck regulation. The unloading event detection circuit is arranged to detect an unloading event, and to assert an unloading event signal if such an event is detected. The inductor current detection circuit is arranged to assert an inductor current detection signal if the inductor current is close to zero. The synchronous switch control logic circuit is arranged to block the synchronous switch from turning on if the unloading event signal is asserted and the inductor current detection signal is not asserted. However, if the inductor current detection signal is subsequently asserted while the unloading event signal is still asserted, the synchronous switch control logic circuit stops blocking the synchronous switch from turning on.

Apparatus and method for faster unloading of transient response in a synchronous buck switching regulator

An error amplifier for closed loop operation is provided. The error amplifier has a track input and a feedback input. During soft-start, a voltage offset is added to the error amplifier input. In one embodiment, the voltage offset is gradually removed during the soft-start.

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Sunnyvale, CA, United States of America

Faruk J Nome