I have build a flashlight with a Arduino duemilanove. Something I'am not sure of is how to use the USB and the switching 5v voltage regulator connected to 5v pin on Arduino. If I not plug in the LiPo battery, and plug in the USB, I get a pop-up "power surge, device exeeded max power limit". Then the USB device is disconnected. I'am not 100% sure why this happends, maybe because of a 330uF capacitor thats used by the switching 5v voltage regulator? That may cause a peak load? There is not allot more thats draining 5v. (leds of the flashlight are not powered by 5v) I understand when you connect a external power supply to Vin or plug, it automatically uses that, but in my situation I use a 5v regulator on 5v pin. Is it posible to use the external 5v supply and still be able to use USB, without draining power from the USB?
Thanks for all your help!