Prevent backfeeding from arduino 5V pin

Question

Hi all,

I have a problem with my arduino nano board. The 5V pin is backfeeding into my circuit when i plugin my USB cable. My circuit draws way to much current than my USB can supply. So the question is: Is there a way to prevent the backfeeding into my circuit? I already considered using diodes but that would create a voltage drop of 0,7V which is a bit much.

Hope i'l get a response soon!

Steve

steve25 · Accepted Answer

Noticed i'm losing 0,8 volts by using a transistor... So i decided to go with the Schottky diode (1N5817) which has only a forward voltage of 0,25V at 30mA. That should do the job!

D_Hersey · Answer

Shottky or Ge?

steve25 · Answer

Thanks for the reply. A Schottky is a good solution because of the low forward voltage. But I think i'l use a transistor. I connect the base to an external power source line. So if the external power source isn't on the transistor is turned off. The 5v pin can't backfeed in this case!

awardautomation · Answer

You could also use a mosfet... They behave like a resistor when on, good ones have very low "on-resistance"

Prevent backfeeding from arduino 5V pin

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