6 way USB lithium charger - with schematic

A universal charger that seems to be aimed at small drones and other devices with swappable lithium cells.

It appears to have six identical charging circuits set at 300-350mA output, keeping it within the range of a 2.1A USB power supply.

The circuitry is unusual in that there are extra components to make it more stable when no cells are plugged in. But it still seems sensitive to external grounded surfaces when a typical mains powered charger is being used.

I'm wondering if the 10K resistor across the LED is possibly to shunt the slight leakage through the 100K resistor, to stop the LED glowing from lithium cell backfeed when the USB power is disconnected.


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