Description
The L6924U is a fully monolithic battery charger that safely charges single-cell Li-Ion/Polymer battery from either an USB power source or an AC adapter. In USB mode, the L6924U supports both low power and high power mode. Alternatively the device can charge from an AC wall adapter. The ideal solution for space-limited portable products integrates the power MOSFET, reverse blocking diode, sense resistor and thermal protection into a compact VFQFPN16 package. When an external voltage regulated adapter or USB port is used, the L6924U works in linear mode, and charges the battery in a constant current constant voltage (CC/CV) profile. Moreover, when a current-limited adapter is used, the device can operate in quasi-pulse mode, dramatically reducing the power dissipation. Regardless of the charging approach, a closed loop thermal control avoids device overheating. The device has an operating input voltage ranging from 2.5 V to 12 V and it allows the user to program many parameters, such as fast-charge current, end-of-charge current threshold, and charge timer. The L6924U offers two open collector outputs for diagnostic purposes, which can be used to either drive two external LEDs or communicate with a host microcontroller. Finally, the L6924U also provides other features like gas gauge function, check for battery presence, and monitors and protects the battery from unsafe thermal conditions.

Features
■ Fully integrated solution, with power MOSFET, reverse blocking diode, sense resistor, and thermal protection
■ Charges single-cell Li-Ion batteries from selectable AC adapter or USB input
■ Programmable charge current up to 1 A in AC adapter mode
■ Programmable charging current in USB mode for both high power and low power inputs
■ 4.2 V output voltage with ± 1 % accuracy
■ Linear or quasi-pulse operating mode
■ Closed loop thermal control
■ Programmable end-of-charge current
■ Programmable charge timer
■ (NTC) or (PTC) thermistor interface for battery temperature monitoring and protection
■ Status outputs to drive LEDs or to interface with a host processor
■ Small VFQFPN 16-leads package (3 x 3 mm)

Applications
■ PDAs, GPS and MP3 players
■ USB powered devices
■ Cellular phones
■ Digital still cameras
■ Standalone chargers
■ Wireless appliances