What kind of circuit do I need where in, I can use USB for charging a li ion Battery as well as use the USB device (For Data Communication) at the same time.
I have used a regular USB device circuit. It all works fine but when I connect the cell with charging circuit to VBus, the device fails to detect.
I guess you have yur ideas.
But we don´t know:
* what USB standard / connector
* what charging current you expect
* what LiIon battery (voltage, capacity...)
* what a "regular USB device circuit"
* how communication vs charging is determined in your device