BetterSense
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ok to power pi throgh GPIO headers?

Sat Sep 14, 2013 9:22 pm

I have read that the GPIO header supplies both 5V and 3.3V. Does that mean if my daughter board has a good 5V power supply, I that I can[*] power the Pi through a ribbon cable through the GPIO header? It would simplify things a lot vs. running a dedicated wire to the micro USB .

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mahjongg
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Re: ok to power pi throgh GPIO headers?

Sat Sep 14, 2013 10:13 pm

Yes, the 5V GPIO pin is directly connected to the 5V logic, the only disadvantage is that you will bypass the polyfuse (in comparison to the path the 5V takes when feeding it through the microUSB).

BetterSense
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Re: ok to power pi throgh GPIO headers?

Sat Sep 14, 2013 10:58 pm

Is there anything I should/can do to prevent Pi from adding noise on my 5V daughter board? Like chokes or something? I am still designing the daughter board. I will have some ADCs and am not experienced with this.

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mahjongg
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Re: ok to power pi throgh GPIO headers?

Sun Sep 15, 2013 7:16 am

a 100uH inductor wont harm, but its not really necessary.

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theoB610
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Re: ok to power pi throgh GPIO headers?

Sun Sep 15, 2013 7:21 am

I think that bypassing the polyfuse in this way will void your warranty, and if there are surges it can cook your pi. This is why I am wary of doing so.

FM81
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Re: ok to power pi throgh GPIO headers?

Sun Sep 15, 2013 7:39 am

theoB610 wrote:I think that bypassing the polyfuse in this way will void your warranty, and if there are surges it can cook your pi.
How ever, he bypasses only the polyfuse, the supressor-diode is still doing his work!?
And if he uses an additional, well rated normal fuse on his self-made-board, then this would be also safe enough?

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A: What does the command 'cat /dev/urandom', can you tell me please?
B: Yeah, that's very simple: It feeds your cat with radioactive material!

BetterSense
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Re: ok to power pi throgh GPIO headers?

Sun Sep 15, 2013 11:11 pm

An can add my own polyfuse. What are the correct specs? Thanks.

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mahjongg
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Re: ok to power pi throgh GPIO headers?

Mon Sep 16, 2013 8:05 am

the original polyfuse is a miniSMDC014 1,1A in 1812 size.

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