Allegro MicroSystems, LLC have announced a new synchronous buck converter with low RDS(on) internal impedance capable of delivering a current of 8 A. The A8672 utilizes valley current mode control, allowing very short on-times to be achieved. This makes it ideal for applications requiring very low output voltages, relative to the input voltage in combination with high switching frequencies.
Valley current mode control gives improved transient response compared to traditional switcher schemes, through the use of a voltage feed-forward loop and frequency modulation during large signal load changes. The A8672 also provides a set of diagnostic flags allowing a host controller to respond to a number of different fault conditions. A fault output indicates over-temperature or single-point failure detection which could indicate 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. A selectable pulse-by-pulse current limit avoids the need 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.