Designed to operate from both USB and ac adapter inputs, the AAT3638 is a Li-Ion/polymer battery charger IC. Designed by Advanced Analogic Technologies (Analogic Tech), the part is built with both a digital thermal loop and a charge-reduction loop. This lets users charge the battery with available current from the USB port while keeping the port voltage regulated. In addition, the thermal loop ,maximizes charging current by measuring internal circuit die temperature and reducing the fast charge current when the die temperature exceeds preset thresholds. The latter feature ensures the battery charge function will not overload the USB port if other system loads share power with the port supply.
For rapid charging, the AAT3638 supports programmable adapter charge current rates up to 1.5 A. USB charge rates can be programmed to two levels (USB high and low) up to a maximum of 0.5 A. USB charging is automatically disabled when an adapter is present. It's housed in a lead-free 16-pin 4- by 4-mm TDFN package. Available immediately, the part sells for $1.64 in 1000-piece lots. More information is available at www.analogictech.com.