Supports Either AC Adapter or USB Charging Advanced

Analogic Technologies (AnalogicTech) announced the AAT3685, a single-cell lithium-ion/polymer battery charger IC capable of operating from either an AC line adapter or USB port output. Depending upon port type, this highly integrated device supports constant charge currents up to 1A. Designed to regulate battery charge voltage and current for any 4.2V lithium-ion/polymer battery cell, the AAT3685 combines a charging device, reverse blocking diode, and current sensing circuit in a compact 3x3mm TDFN package. A Charge Reduction Loop minimizes charge time by allowing users to charge the battery with available current from the charge supply while keeping the port voltage regulated. Such dynamic control of the charge current enables the fastest possible charge time while sharing the port supply. This feature automatically compensates for voltage sags and ensures the battery charger will not overload the USB port if other system applications share power with the port supply.

The device also offers protection features to ensure the integrity of the charger and the battery. Battery temperature and charge state are continually monitored for fault conditions. Over-voltage and over- temperature circuits automatically shut down the device in the event of a failure. Status monitor output pins are provided to drive two external LEDs to indicate battery charge status. The device also adds a serial interface output which can report any of 14 different status states to a microcontroller. The AAT3685 is rated over the -40 degrees C to +85 degrees C temperature range and is immediately available in a Pb-free, thermally-enhanced, 12-pin, 3x3mm TDFN package. The device sells for $1.20 in 1000-unit quantities.