Charger and step-down convertor come together

New from Advanced Analogic Technologies, the AAT2556 is the company's first multifunction SystemPower IC to combine a battery charger and step-down convertor in a single package.

New from Advanced Analogic Technologies, the AAT2556 is the company's first multifunction SystemPower IC to combine a battery charger and step-down convertor in a single package.

This new device offers a highly compact and power efficient solution for a growing number of single-cell lithium-ion/polymer battery-based ultraportable systems, such as Bluetooth headsets, handheld GPS devices and high-end portable music players.

"Ultraportable devices that operate from small lithium-ion batteries need high power efficiency in an extremely small footprint", noted Bill Weiss, Product Line Director for AnalogicTech.

"By sizing the convertor appropriately for these applications and integrating a battery charger into the same device, the AAT2556 allows designers to maximise power efficiency while occupying only 9mm2 of PCB area".

"Previous solutions occupy 67% more PCB area than the AAT2556 does".

The step-down convertor in the AAT2556 delivers up to 250mA output current.

It operates in both fixed and variable frequency modes to support high efficiency levels that range up to 96%.

No load quiescent current is a low 30uA.

A 1.5MHz switching frequency minimises the sise of external components and keeps switching losses low.

The battery charger is a complete constant current/constant voltage linear charger.

Designed to operate from USB or AC adapter inputs across a 4.0 to 6.5V input range, it integrates a charging device and reverse blocking diode to regulate battery charge voltage and current for single-cell lithium-ion/polymer batteries.

Charging current is programmable from 15 to 500mA via an external resistor.

To ensure device integrity, the AAT2556 adds overvoltage, overcurrent and thermal protection circuits.

The AAT2556 is the second production device developed using AnalogicTech's ModularBCD process technology.

Unlike conventional BCD technologies, this new process uses a low-temperature, CMOS-like flow capable of achieving high yields while ensuring device performance and electrical isolation.

By allowing AnalogicTech's designers to easily add or remove modules and devices for different voltages, this highly modular new process promises to vastly simplify analogue and mixed-signal circuit reuse.

The AAT2556 is specified over the -40 to +85C temperature range.

It is immediately available in a Pb-free, compact 3 x 3mm, 12-pin TDFN package.

The device sells for $1.68 each in 1000-piece quantities.

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