Description
The STC4054 is a constant current/constant voltage charger for single cell Li-Ion batteries. No external sense resistor or blocking diode is required and its ThinSOT package make it ideally suited for portable applications. The STC4054 is designed to work within USB power specifications. An internal block regulates the current when the junction temperature increases, in order to protect the device when it operates in high power or high ambient temperature.
The charge voltage is fixed at 4.2V, and the charge current limitation can be programmed using a single resistor connectd between PROG pin and GND. The charge cycle is automatically terminated when the current flowing to the battery is 1/10 of the programmed value. If the external adaptor is removed, the STC4054 turns off and a 2µA current can flow from the battery to the device. The device can be put into Shutdown Mode, reducing the supply current to 25µA. The device also has a charge current monitor, under voltage lockout, automatic recharge. The device is packaged in TSOT23-5L.

Feature summary
■ Programmable charge current up to 800mA
■ No external MOSFET, sense resistors or blocking diode required
■ Constant current / constant voltage operation
   with thermal regulation to maximize charge
   rate without risk of overheating
■ Charges single cell li-ion batteries directly from USB port
■ Preset 4.2V charge voltage with 1% accuracy
■ Automatic recharge
■ Single charge status output pin
■ Charge current monitor output for gas gauging
■ C/10 Charge termination
■ 25µA supply current in shutdown mode
■ Low battery voltage detect for precharge setting
■ Soft-start limits inrush current
■ TSOT23-5L package

Applications
■ Cellular telephones
■ PDAs
■ Bluetooth applications
■ Battery-powered devices