I'm going to be working on a project from a DC power supply, and I need to know the maximum current the Raspberry Pi can handle from the USB port. I know my wall wart adapter that came with my Pi outputs 5volts at 1000mA, but how high can I crank up the amperage without destroying my Pi?
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Do you mean you want to back-power the pi via the USB ports? elinux.org/RPi_Hardware#Power (3rd list, 4th bullet point)– goldilocks ♦Aug 24, 2013 at 19:32
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2 Answers
Current (amperage) doesn't work like that. The device draws the current it requires, and the power supply needs to provide that or higher. For example, if you were to switch to a 2A (2000mA) supply, it would operate fine (assuming 5V of course).
So the answer is there is no limit. Just make sure you provide the appropriate voltage and at least the actual current the Pi (and any attachments) will require.
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There is probably a limit (though I don't know what it is) to the amperage the Pi can pass on to the attached USB/GPIO peripherals though. Aug 25, 2013 at 2:19
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I took the question to mean "how much current can be supplied to the mini-USB power input". If the question is "how much current can be drawn from one of the on-board USB sockets", then yes, there is most definitely a limit. Aug 25, 2013 at 9:59
there's a short-circuit protection polyfuse, that's supposed to trip when the current drawn from the power supply exceeds 1.1A (constant, or a little bit higher for the short bursts). considering the RasPi consuming about 0.7A, your project may safely draw about half-an-ampere.
if you shorten the polyfuse, you may get higher currents, provided your power supply can handle them, but you may eventually burn and damage PCB tracks depending on how high you'd go.
also, earlier versions of RasPi included separate 150mA polyfuses for every USB port, you may check for these if your board is not a recent one.
