This part is a kind of semiconductor called LN2054.
Function of this product has Standalone Linear Li-Ion Battery Charger.
Manufacturers : Natlinear
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LN2054 Standalone Linear Li-Ion Battery Charger with Thermal Regulation ■ General Description The LN2054 is a complete constant-current /constant -voltage linear charger for single cell lithium-ion batteries. Its ThinSOT package and low external component count make the LN2054 ideally suited for portable applications. Furthermore, the LN2054 is specifically designed to work within USB power specifications. No external sense resistor is needed, and no blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The LN2054 automatically termi [ ... ]