I2C 1cell 1.25A Buck battery charger with OTG

The bq24157S 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 IC integrates a synchronous PWM controller, power MOSFETs, input current sensing, high-accuracy current and voltage regulation, and charge termination, into a small DSBGA package.

The IC 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 battery voltage and user-selectable minimum current level. During normal operation, the IC 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 can be reported to the host using the I2C interface. During the charging process, the IC monitors its junction temperature (TJ) and reduces the charge current after TJ increases to about 125°C. To support a USB OTG device, bq24157S can provide VBUS (5.05 V) by boosting the battery voltage. The IC is available in 20-pin DSBGA package.