For questions about the TP4056 lithium-ion battery charger IC.
From the datasheet:
The TP4056 is a constant-current/constant-voltage linear charger for single cell lithium-ion batteries. The charge voltage is fixed at 4.2 V, and the charge current can be programmed externally with a single resistor. The TP4056 automatically terminates the charge cycle when the charge current drops to 1/10th of the programmed value after the final float voltage has been reached. Other features include current monitor, under voltage lockout, automatic recharge, and two status pins to indicate charge termination and the presence of an input voltage.
