What this linear charger does for a Li-Ion/Polymer pack
The BQ2057SNTR is a linear charge-management IC from Texas Instruments designed specifically for single-cell lithium-ion and lithium-polymer battery chemistries. As a linear topology, it regulates charge current and voltage without a switching inductor — the pass element dissipates the voltage drop as heat, so the board layout needs a good thermal path under the IC.
Confirming the charge current ceiling before layout
For a typical single-cell Li-Ion/Polymer charge profile, the IC terminates at 4.2 V with a constant-current / constant-voltage algorithm; the designer picks the sense resistor value to match the pack's C-rate.
Confirm with your EMS that the feeder setup can handle Bulk tubes, or request a reeled variant if the BOM quantity justifies a reel fee.
Sourcing the BQ2057SNTR against a BOM line
The base product number BQ2057 covers multiple package and temperature variants; verify that the suffix SNTR matches your required footprint and operating range before placing the order.