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The bq24155 is a compact, flexible, high-efficiency, USB-friendly switch-mode charge management device for single-cell Li-ion and Li-polymer batteries used in a wide range of portable applications. The charge parameters can be programmed through an I²C interface. The bq24155 integrates a synchronous PWM controller, power FETs, input current sensing, high-accuracy current and voltage regulation, and charge termination, into a small WCSP package.

The bq24155 charges the battery in three phases: conditioning, constant current and constant voltage. The input current is automatically limited to the value set by the host. Charge is terminated based on user-selectable minimum current level. A safety timer with reset control provides a safety backup for I²C interface. During normal operation, bq24155 automatically restarts the charge cycle if the battery voltage falls below an internal threshold and automatically enters sleep mode or high impedance mode when the input supply is removed. The charge status is reported to the host using the I²C compatible interface.

During the charging process, the bq24155 monitors its junction temperature (T_J) and reduces the charge current once T_J increases to approximately 125°C. The bq24155 is available in 14-pin QFN package.