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Charger IC powers up to two Li-ion cells in series

Posted: 21 Dec 2007 ?? ?Print Version ?Bookmark and Share

Keywords:Li-ion battery cells? battery charger IC? CMOS?


Advanced Analogic Technologies Inc. has introduced the AAT3663, the first in a family of 1A linear battery charger ICs capable of charging up to two Li-ion cells in series. Designed to operate from either an AC adapter or a USB port, the device features AnalogicTech's innovative Digital Thermal Loop charge reduction circuit that monitors the internal die temperature and gradually steps down the charge current to avoid thermal shutdown.

A growing number of products, from portable media players and digital cameras to POS solutions and high-end handsets are powered by two Li-ion cells connected in series. By supporting input voltages up to 13.2V, the AAT3663 offers designers the opportunity to replace larger and more expensive discrete charging solutions with a highly integrated and more cost effective alternative.

The AAT3663 operates across a 4V to 13.2V input voltage range and supports user programmable charge current from 100mA up to 1A via an external resistor. Quiescent current is less than 6?A.

The device features an intelligent digital thermal loop charge reduction circuit that optimizes battery charge rate by constantly measuring die temperature and adjusting the charge current to compensate for thermal conditions. Unlike many competitive charger ICs, this closed loop thermal management system allows the charger to continue charging even under harsh environmental conditions, therefore minimizing charge time.

The charger IC also has a programmable charge termination current feature that sends the device into sleep mode if the charging current dips below a pre-defined threshold. An integrated programmable charge timer can be used to shut down charging functions if a defective battery cell or a disconnection to the battery current path is detected.

The AAT3663 continuously monitors battery temperature and charge state for fault conditions. To protect the charging device and the battery under charge, integrated overtemperature, shortcircuit, overvoltage and overcurrent protection circuits automatically shuts down the device if a fault occurs.

The AAT3663 is fabricated in AnalogicTech's proprietary ModularBCD process. Compared to linear-IC legacy fabs and generic digital CMOS foundries, ModularBCD provides more cost-effective, modular fabrication of analog, power and mixed-signal ICs by monolithically integrating fully isolated CMOS at multiple voltages, complementary bipolar transistors and robust power devices. This process avoids complex and expensive techniques such as epitaxy and high-temperature diffusion. Devices manufactured in ModularBCD offer higher efficiency, smaller size and higher levels of integration than those fabricated in many other processes.

Specified for operation across the -40C to 85C temperature range, the AAT3663 is available in a thermally enhanced 14-pin, 3mm x 3mm TDFN package.

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