2-cell Li-Ion linear charger with programmable current
The Texas Instruments BQ2057WTS is a linear battery charger IC designed for 2-series Lithium-Ion or Lithium-Polymer packs, terminating at 8.4V. It operates from a supply up to 15V and delivers a constant charging current that the designer sets with a single external resistor — no I2C or SMBus needed.
Programmable current and 8.4V termination
The charge current is constant and programmable — the designer picks the resistor value to set the current level for the battery capacity. The charger terminates at 8.4V, the full-charge voltage for a 2-cell Li-Ion or Li-Poly stack. The only programmable feature is current; there is no digital interface, no timer, and no temperature-qualified termination. The charger relies on the external resistor and the internal voltage-regulation loop to end the charge cycle.