he TP4057 is a complete single-cell Li-Ion battery charger with battery positive and negative reverse polarity protection with constant current / constant voltage linear control. Its SOT26 package and fewer external components make the TP4057 ideal for portable applications. The TP4057 is suitable for USB power and adapter power supplies. Due to the internal PMOSFET architecture and anti-reverse charging path, no external sense resistors and isolation diodes are required. Thermal feedback automatically adjusts the charge current to limit chip temperature during high power operation or high ambient temperature conditions. The full voltage is fixed at 4.2V , and the charging current can be externally set by a resistor. When the battery reaches 4.2V , the charging current drops to the set value of 1/10 , and the TP4057 will automatically terminate charging. When the input voltage (AC adapter or USB power) is removed, the TP4057 automatically enters a low current state with a battery leakage current below 2uA . Other features of the TP4057 include a charge current monitor, undervoltage lockout, automatic recharge, and two status pins that indicate the end of charge and input voltage input. Downloads Datasheet
