2-cell Li-ion charger with programmable current
The Texas Instruments BQ2057TTSTR is a charge management IC designed specifically for 2-series Lithium Ion or Lithium Polymer battery packs. It delivers a regulated 8.2 V battery pack voltage and supports constant-current charging that is programmable via an external resistor — no I²C or SMBus needed, just a resistor to set the charge rate.
It is not rated for extended outdoor exposure or under-hood automotive use without additional thermal derating analysis.