Author Options:

USB "charging done LED" circuit? Answered

Does anyone have a very simple circuit (newb here) that can be used to indicate that a USB-based "charging is complete" or "is charging" (whichever is easiest). In other words, say if it's taking 200ma or more, light up an LED.

Not a full charger btw, just something that I can plug in between anything - computer/car/ac-charger - and the device.

This would be useful on devices that have no indicator at all or on things like phones that have their LCDs dimmed when charging.



.  I'd use an op-amp as a comparator with a very-low-ohm resistor in series with the load to supply V+.  YMMV