Charger chip is faster and more reliable

A novel dual-path lithium-ion/polymer battery charger IC allows users to charge the battery with available current from the USB port while keeping the port voltage regulated.

Designed to operate off both USB and AC adapter inputs, the AAT3686 lithium-ion/polymer dual-path battery charger IC from Advanced Analogic Technologies features both an innovative digital thermal loop and a charge reduction loop that allows users to charge the battery with available current from the USB port while keeping the port voltage regulated.

The latter feature ensures the battery charge function will not overload the USB port if other system loads share power with the port supply.

As an example, if a portable device is being charged at 500mA using a USB port, and it is required to use the device while it is charging, the voltage can easily fall out of regulation if worst-case current budgets have not been set by the designer.

The AAT3686 simplifies design, reduces charging time, and increases system reliability by integrating a charge reduction function that automatically compensates for voltage sags and throttles back the charge current depending on how much current other loads on the device are consuming.

Extending AnalogicTech's growing battery charger IC product portfolio, the AAT3686 also adds a digital thermal loop control system that maximises charging current by measuring internal circuit die temperature and reducing that fast charge current when the circuit die temperature exceeds preset thresholds.

For rapid charging, the AAT3686 supports programmable adapter charge current rates up to 1.5A.

USB charge rates can be programmed to two levels, USB high and USB low, up to a maximum current level of 500mA.

USB charging is automatically disabled when an adapter is present.

The AAT3686 provides a variety of features to protect the integrity of the charging device, the control system, and the battery under charge.

Battery temperature and charge state are constantly monitored for fault conditions.

Overvoltage and overtemperature protection circuits automatically shut down the device in the event of a failure.

Status monitor output pins indicate battery charge status by directly driving two external LEDs.

The AAT3686 can also report up to 22 different charging status states to a microcontroller via a serial interface output.

The AAT3686 is immediately available in a Pb-free, thermally enhanced, 16-pin 4 x 4mm TDFN package.

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