Tiny PMUs combine 3 step-down DC/DC converters

Advanced Analogic Technologies Inc. has developed two new mini-power management units (PMUs) that combine three step-down DC/DC converters in a single monolithic IC.

Targeted at portable devices with rapidly evolving feature sets, the 3-channel AAT2784 and AAT2785 allow designers to add one 1.5A synchronous step-down converter and two 300mA synchronous step-down converters or one 1.5A synchronous step-down converter and two 600mA synchronous step-down converters, respectively, without radically altering their existing core system design or adding numerous discrete devices.

The AAT2784 and AAT2785 operate off an input voltage range of 2.7 to 5.5V. Outputs are adjustable from 0.6V to V_in. Both devices employ a low noise architecture that reduces output ripple by 25 percent and spectral noise by up to 50 percent. With efficiency levels exceeding 95 percent, the new devices help reduce power consumption and extend battery life. Quiescent current is a low 50 ?A/channel. Transient response time is typically In addition, each of the three regulators in the AAT2784 and AAT2785 has an independent enable pin. A high 1.8MHz switching frequency helps minimize the size of external components and reduce PCB footprint. Also, an integrated internal soft start function limits current surge at the input and eliminates output voltage overshoot. Both devices also feature over-temperature and current-limit protection.

"Oftentimes portable system designers want to expand the feature set of an existing handset, portable media player or other system, but don't have the lead time to redesign the system PMU and still meet a rapidly closing market window," explained Bill Weiss, product line director for AnalogicTech. "By offering designers three independently-controlled switching regulators sized to power a processor core, an I/O and a DSP, ASIC or RF circuitry in a single compact package, the AAT2784 and AAT2785 combine the advantages of functional integration, including simpler component selection, reduced BOM, minimized PCB requirements and shorter time-to-market, with the flexibility and electrical performance of a discrete approach."

The AAT2784 and AAT2785 are qualified across the -40°C to 85°C temperature range and are housed in a Pb-free, 16-pin TDFN34 package. The AAT2784 is available for $1.70 and the AAT2785 for $1.84, both in 1,000-unit quantities.