Charger chip adds flexibility

The AAT3685 single-cell lithium-ion/polymer battery charger IC can be programmed for two separate constant current charge levels up to 1A.

Cellphone and other battery-powered device manufacturers are always trying to give customers as much flexibility as possible.

AnalogicTech's AAT3685 single-cell lithium-ion/polymer battery charger IC can be programmed for two separate constant current charge levels up to 1A, so users can charge their devices from either an AC source or any USB port without compromising their fast charge rate.

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 3 x 3mm TDFN package.

An innovative charge reduction loop minimises 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 that the battery charger will not overload the USB port if other system applications share power with the port supply.

The AAT3685 also offers a wide variety of 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 that can report any of 14 different status states to a microcontroller.

The AAT3685 is rated over the -40 to +85C temperature range and is immediately available in a Pb-free, thermally enhanced, 12-pin, 3 x 3mm TDFN package.

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