Overview: 

The AX4057 is a complete single-cell lithium-ion battery charge management IC with constant current/constant voltage. Its small SOT package and low external component count make it ideal for portable applications, and the AX4057 is suitable for both USB power and adapter power operation. The internal PMOSFET architecture and the anti-reverse charge circuit eliminates the need for external detection resistors and isolation diodes. Thermal feedback regulates the charging current to limit the chip temperature during high power operation or high ambient temperature conditions, the charging voltage is fixed at 4.2V, and the charging current can be set externally via a resistor. The AX4057 will automatically terminate the charge cycle when the charge current drops to 1/10 of the set value after reaching the final float voltage. When the input voltage (AC adapter or USB power supply) is taken off, the AX4057 automatically enters a low current state, reducing the battery leakage current to less than 2uA. The AX4057 can also be placed in shutdown mode to reduce the supply current to 25uA. Other features of the AX4057 include a charge current monitor, undervoltage lockout, automatic recharge, and a status pin to indicate the end of charging and input voltage access. The chip integrates a dual-light indicator for charging status, which can be configured to illuminate red when charging and green when full. 

Features:

- Programmable charging current 500mA.

- No external MOSFETs, detection resistors or isolation diodes required.

- Constant current/constant voltage operation with thermal regulation to maximise charge rate without risk of overheating.

- 4.2V pre-charge voltage with ±1% accuracy.

- Charge current monitor output for battery level detection.

- Automatic re-charging.

- Dual outputs for charging status, no battery and fault status indication.

- C/10 Charge termination.

- Standby mode quiescent current is 25uA.

- 2.9V trickle charge with battery anti-reverse connection function.

- Soft-start to limit inrush current.

- SOT23-6L package.

-40°C to +85°C temperature range.

Applications:

- Mobile phones, PDAs, rechargeable batteries.

- MP3, MP4 player.

- Bluetooth, GPS navigator.

- Portable device charger.