High-current synchronous buck regulator with integrated switches

March 19, 2014 // By Graham Prophet
A8672 from Allegro MicroSystems is a synchronous buck regulator IC capable of delivering high currents (up to 8A) through the use of low on-resistance internal switches.

It uses valley current mode control, which allows very short on-times to be achieved and inherently provides improved transient response over traditional switching schemes through the use of a voltage feed-forward loop and frequency modulation during large signal load changes.

A8672 includes a comprehensive set of diagnostic flags, allowing the host platform to react to different fault conditions. A fault output indicates when either the temperature is becoming unusually high, or a single point failure has occurred - such as the switching node shorted to ground or the timing resistor going open-circuit.

A “power OK” output is also provided after a fixed delay to indicate when the output voltage is within regulation. The selectable pulse-by-pulse current limit avoids the need to oversize the inductor to cope with large fault currents.

Typical applications include servers and networking systems that require 5V or 12V input stepdown conversions at high output current.

The A8672 is available in a 4 x 5 mm, 28-contact QFN package (suffix EG) with exposed pad for enhanced thermal performance.

Allegro MicroSystems; www.allegromicro.com