Can you draw the entire 500 mA that the usb connection provides through the 5v pin, or is it bound by the 200 mA total for the board? (well less what the board itself is using). Sorry about all the power questions, but the arduino page is sorely lacking in info like this. I assume it's because it's geared for beginners and such.
Thanks!
Allowing about 100 mA for the Arduino you should be able to draw about 400 mA from the 5V pin when running off USB power.
Thanks, just didn't want to blow any chips it may be running through before it goes out the 5v pin. Eh I've been avoiding it but I guess I'll get the Arduino schematics and sort this kind of stuff out for myself. Probably learn a whole lot more that way anyway.
Thanks for the answer!
The 5v doesn't go thru any chips between the USB port and the power header - just the resettable polyfuse that's meant to protect the PC USB port from excessive current draw.
Hmm - does if go thru the FET that's part of the auto-voltage select?
FDN340P. Okay, it goes thru 1 chip.
It's a 2A part tho. The PTC or the PC USB source might likely go first. Even if you slammed it with 500mA draw all at once, it's 70mOhm Rds means 35mW of heat dissipation, it should be okay with that.
Thanks again. I may just run a separate 5v and 3.3v rail to power the sensors and do away with siphoning off the uno anyway. Probably safer in the long run
Could be. Don't forget to connect all grounds together.