A4491: Triple Output Step-Down Switching Regulator

Designed to provide the power supply requirements of printers, office automation, industrial, and portable equipment, the A4491 provides three high current, high performance, switching regulator outputs in a single package, saving space, cost and component count.

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. Independent Enable pins simplify power sequencing and shutdown capabilities, and a power-on-reset (POR) circuit with user configurable delay indicates when enabled regulators are in specification. The POR 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.

Output current capability is ~4.5 A total for all 3 outputs, depending on the combinations of Vin and each Vout level.

The A4491 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.

Applications

• Photo, inkjet, and portable printers
• Set-top boxes
• Tablet computing
• Other consumer electronics applications
• Point-of-sale applications
• Security systems
• Gaming machines
• Other industrial applications