A4490: Triple Output Step-Down Switching Regulator

Designed to provide the power supply requirements of printers, office automation, industrial, and portable equipment, the A4490 provides three high current, high performance, switching regulator outputs with independent soft start.

High frequency switching allows selection of inexpensive inductors and small ceramic output capacitors. The turn-on cycles of the regulators are interleaved to minimize stresses on the input capacitors and to reduce EMI. A charge pump is used to provide the supply for driving the power switches, ensuring operation at very wide operating duty cycles and avoiding the need for power-draining clamp circuits.

A power-on-reset circuit with user configurable 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 while the switchers continue to operate down to the shutdown level.

Internal diagnostics provide comprehensive protection against overloads, input undervoltages, and overtemperatures. The A4490 is provided in a 20-contact, 4 mm × 4 mm, 0.75 mm nominal overall height QFN, with exposed pad for enhanced thermal dissipation. It is lead (Pb) free, with 100% matte tin leadframe plating.