USB "charging done LED" circuit?

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.


Picture of USB
NachoMahma7 years ago
.  I'd use an op-amp as a comparator with a very-low-ohm resistor in series with the load to supply V+.  YMMV