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Step-down switching regulator has three adjustable outputs

Posted: 23 Apr 2008 ?? ?Print Version ?Bookmark and Share

Keywords:switching regulators? high-current outputs? EMI?

Allegro MicroSystems Inc. has announced a step-down switching regulator, the A4490, which provides three high-current adjustable outputs with an input voltage range of 4.5V to 34V. Each output is adjustable from 0.8V to 5V with a maximum current of 2A. Multiphase switching reduces EMI and minimizes stress on input capacitors by interleaving the turn-on cycle of the regulators. Features like soft start, power-on-reset output and a small 4mm x 4mm QFN package make this new device suitable for many portable, office automation and consumer applications.

The 550kHz fixed frequency switching allows selection of small, inexpensive inductors and ceramic output capacitors. A charge pump is used to provide the supply to drive the power switches to ensure operation at very wide operating duty cycles and to avoid the need for power draining clamp circuits.

A power-on-reset circuit with programmable delay indicates when enabled regulators are in specification. The power-on-reset flag also indicates when the input voltage drops below specification, giving the system controller advance warning whilst the switchers continue to operate down to the shutdown level. Internal diagnostics provide comprehensive protection against, overloads, input under voltages and over temperatures.

Allegro's A4490 is supplied in a low-profile (0.75mm) 4mm x 4mm, 20-pin QFN package with exposed power tab.

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