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I have 3 micro-controllers that will be connected to a battery, and I need to provide each of them between 3 and 5 volts maximum.

I have 3V batteries but they do not seem to provide enough power, while putting to of them in series would fry the chips as it busts the 6 volts max.

My question is, if I provide 9 volts to 3 chips connected in series, would current drop be distributed evenly to 3V across all chips, or would for example fry the first one?

schematic

simulate this circuit – Schematic created using CircuitLab

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    If you connect micro-controllers in series like that, it's unlikely you'll fry them, but they won't work reliably. They need a constant voltage to operate correctly, and if you put them in series, the load on one will change the voltage on the others. – PMF Feb 26 at 7:30
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    Additionally, if one chip doesn't work with 3V, 3 chips won't work with 9V. You'll probably need slightly more than 3V per chip. – PMF Feb 26 at 7:33
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    So your batteries are the right voltage, but they don't provide enough current? How about putting multiple batteries in parallel? That would keep the same voltage, but would raise the maximum current – chrisl Feb 26 at 10:12
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    would current drop be distributed evenly ... you have a misunderstanding ... there is no such thing as current drop ... it is voltage drop that would be distributed ... the current would be the same through each of the chips ... the voltage drop would be evenly distributed only if the chips were completely identical and they executed the same program in sync ... so no, in real life, the voltage would not be distributed evenly – jsotola Feb 26 at 16:54
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If you put three resistors of the same value in series, then you would get equal voltage division between them.

But chips are not like resistors. Their current usage is not constant and typically vary by orders of magnitude even within each clock cycle. See why this would be a problem?

If you have good 3V batteries that supply 3V up to the maximum current that the chips can draw, and the chips are rated to run reliably at 3V then there is another problem. Maybe you need decoupling capacitors across the chips?

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  • Thank you! What would the decoupling capacitors do specifically? – B7th Feb 26 at 8:54
  • Does one chip work at 3V? – PMF Feb 26 at 14:27
  • Chips can use different amounts of current at different times, and that amount can change abruptly.sometimes the power source can not supply these bumps fast enough, so the caps help smooth it out. – bigjosh Feb 27 at 20:08
  • >Does one chip work at 3V? - depends on the chip! What chip are you using? – bigjosh Feb 27 at 20:08

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