Electronic – put a Schottky diode and a resistor between a USB connector and a TP4056 charger IC

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I've found this useful explanation for a load sharing circuit based on the established TP4056 charger IC:


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Now I would like to know why there is a SS14 Schottky diode and a 0.4 ohm resistor between the USB connector and the TP4056 charger IC.

And would it work without it too?

Best Answer

It is presumably to avoid power from the cell discharging into the USB port.

Particularly of the host/charger is powered off.

The 0.4 ohm resistor will help reduce the power dissipated within the IC at high charging currents.