Theale, UK AnalogicTech has introduced a highly integrated battery charger IC designed to operate from USB port inputs. The AAT3688 features an innovative charge reduction loop that reduces charge time by automatically monitoring the USB port voltage and dynamically adjusting the current while the battery is charging. The function dramatically simplifies this task, allowing users to charge faster and more efficiently from the USB port by automatically adjusting for voltage sags and reducing the charge current as other functions on the host device consume more power. Part of AnalogicTech’s rapidly expanding BatteryManager product family, the compact AAT3688 integrates a charging device, reverse blocking diode, and current sensing circuit in a small 3 x 3 mm TDFN package. Covering a 4 V to 5.5 V input range, the device is designed to regulate voltage and current for 4.2 V lithium ion/polymer battery cells. Charge current on the AAT3688 can be programmed for two separate levels, USB High and USB Low, between 50 mA and 500 mA, depending upon port type.
To ensure safety and system reliability, the AAT3688 offers a number of safety features including the ability to monitor battery temperature and charge state for fault conditions. If an over-voltage or over-temperature failure occurs, the device automatically shuts down to protect the charging device, the control system, and the battery under charge. Status monitor output pins can be used to directly drive two external LEDs to indicate battery status. The AAT3688 also includes a serial interface output that reports any one of 14 status states to a microcontroller. While a growing number of portable devices are now designed to charge solely off a USB port, it is not a trivial task for designers to determine how much power other functions in the portable device are drawing from the USB source. Designers have typically taken an all-or-nothing approach and set arbitrary worst-case current budgets to maintain port integrity and protect the host system. AnalogicTech’s AAT3688 dramatically improves and simplifies this task. The AAT3688 is immediately available in a Pb-free, 12-pin, 3x3mm TDFN package and is rated over the -40 °C to +85 °C temperature range.
AnalogicTech , Theale, UK. www.analogictech.com.