TP4056 Micro USB 5V 1A 18650 Lithium Battery Charger Board Protection Module The TP4056 is a complete constant-current / constant voltage linear charger for single cell lithium-ion batteries. Its SOP package and low external component count make the TP4056 ideally suitable for portable applications. Furthermore, the TP4056 can work within USB and wall adapter. No blacking diodes are required due to the internal PMOSFET architecture and have prevent to negative charge current circuit. Thermal feedback regulates the charge current to limit the die temperature. The charge voltage is fixed at 4.2V, and the charged current can be programmed external with the single resistor. the TP4056 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached.