Components

High-Current Synchronous Buck Regulator with Fault and Power OK Pins

Allegro MicroSystems, LLC announced a new synchronous buck converter capable of delivering high current due to low RDS(on) internal switches. Allegro’s A8672 utilizes valley current-mode control, allowing very short on-times to be achieved. This makes it suited for applications that require very low output voltages, relative to the input voltage in combination with high switching frequencies. Typical applications include servers and networking systems that require 5 V or 12 V input step down conversions at high output current. Valley current-mode control inherently provides improved transient response over traditional switcher schemes, through the use of a voltage feed-forward loop and frequency modulation during large signal load changes.

The A8672 includes a comprehensive set of diagnostic flags, allowing the host platform to react to a myriad of different fault conditions. A fault output indicates when either the temperature is becoming unusually high, or a single point failure has occurred; for example, the switching node (LX) shorted to ground, or the timing resistor going open-circuit. A Power OK (POK) 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 requirement to oversize the inductor to cope with large fault currents.

Allegro's A8672EEGTX-T is targeted at the industrial, consumer and computer markets and is available in a 4 mm x 5 mm, 28-contact QFN (suffix EG) with exposed pad for enhanced thermal performance. It is priced at $1.42 in quantities of 1,000.

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