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GPIO +5v max current?

Thu Aug 09, 2012 11:25 pm

I would like to build my own case for the PI, and set up a fan with the 5v GPIO pins, however I am wondering what current I can expect to have available at start-up from that, or if it would be better just to cut up a usb cord and get it from that? (the fan in question uses .2 amps max at start-up, measured using my $5 multimeter - hopefully that isn't too much to ask for)

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Re: GPIO +5v max current?

Thu Aug 09, 2012 11:39 pm

There aren't any 5V GPIO pins on the Raspberry Pi, they are 3.3V. You will have to put in some sort of interfacing circuit between the Raspberry Pi GPIO pin, and the 5V circuit running the fan.
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Re: GPIO +5v max current?

Fri Aug 10, 2012 12:46 am

ok, allow me to clarify then: if I connect a fan between the +5v and the ground, how much current am I allowed to use?

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Re: GPIO +5v max current?

Fri Aug 10, 2012 1:10 am

According to the schematic there is a 1A fuse and from what others have said the Raspberry Pi uses about 700mA so 200mA is what your left with to use for USB and anything over the +5v GPIO pin.

So yes you could use it on the +5v GPIO pin but then there would be nothing left for the USB.

Also because it is so close to the fuse limit any slight change could cause the fuse to engage.


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Re: GPIO +5v max current?

Fri Aug 10, 2012 3:03 pm

OK, I will splice the usb cord and put the fan before the Pi's power - thanks for the answer

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Re: GPIO +5v max current?

Sun Aug 26, 2012 2:09 am

According the Wiki and other threads on this forum, the RPi has 3 fuses.
F1 and F2 are on side of USB ports, with 140mA limit (each USB port).
F3 is near the micro USB plug (on opposite side), and is 750mA limited.
And EXIST's a 5V GPIO. P1 on GPIO connector is 3V3. The pin on other row is 5V. Find it on the Wiki.

So, since RPi can consume 700mA on full load with USB loads, there's no much current to 5V GPIO.
If you don't use USB devices on RPi (use devices on powered USB hub instead), you can have 200~300 mA on 5V GPIO.

There people putting 5V directly on 5V GPIO instead of micro USB plug. You will lose the F3 fuse protection in case of short circuit.
Or you can just make a bridge (with wire) over the F3 fuse and keep using the micro USB plug to power the entire board.
To avoid the current limit on USB ports of RPi, is possible to solder wires on USB plug from 5V GPIO or even micro USB plug.

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