What this 2-cell Li-ion charger does on your board
The Texas Instruments BQ2057WSNTR is a linear battery charger IC designed specifically for a 2-cell series Lithium Ion or Lithium Polymer stack, terminating at 8.4 V pack voltage. Charge current is constant and programmable via an external resistor — no I²C, no SMBus, just a resistor from the PROG pin to ground. Supply input can go up to 15 V. The device operates from -20°C to 70°C.
Package and rework — the SOIC-8 is your friend
The SOIC-8 package has a 0.154 inch body width.
Lifecycle reality — obsolete, but still sourcable
For new designs, look at the BQ2057 series base part number — the BQ2057W (non-tape) variant may still be available through some channels, but TI has moved on to newer charger families like the BQ240xx or BQ256xx for 2-cell applications.