The BQ2057PDGKG4 is a single-cell linear charger for Lithium Ion and Lithium Polymer packs, with a battery regulation voltage of 4.1V — not the more common 4.2V ceiling. That 100 mV difference means it is suited for cells whose top-of-charge voltage is specified at 4.1V, which includes some early-generation and specialty Li-Ion chemistries. Charging current is constant and programmable via an external resistor; the device does not include a charge-termination timer or temperature monitoring on-chip, so the BOM should budget for those functions externally if the application requires them. Supply voltage range extends to 15 V max.
Package and mounting
The 0.65 mm pitch is layout-friendly for two-layer boards, though the thermal pad on the VSSOP variant should be connected to a copper plane for heat spreading during constant-current charging. Operating temperature range is -20°C to 70°C ambient, which covers most portable and consumer equipment but excludes automotive cabin or outdoor enclosure use without active cooling.
Texas Instruments has marked the BQ2057PDGKG4 as Obsolete. For existing designs, the procurement path is through independent distribution or excess inventory channels. The tube quantity should be verified against the BOM line quantity to avoid partial-tube shortages.