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Powering analog sensors with digital output pins

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I have an application where I need to hookup 10-12 hall effect sensors to an Arduino mega - each sensor consumes ~7mA.  I would like to power the unit from a large-ish LiPo battery and am curious as to the pros/cons of powering the sensors from the +5V pin or from digital pins set as outputs?  It seems like using digital pins would allow me to control when I actually power the sensors and provide greater flexibility in terms of maximizing runtime.  Are there any drawbacks to this approach - I am assuming that the pins provide a reliable 5V source when set as an output?  Any insight would be appreciated!

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  • I've done this (or similar things) often. You have to be careful that the digital output pins can cope with the current and, in addition, that the voltage drop at the current in question is OK. Digital output pins are often a little noisier than the supply and the voltage drop is often modulated a little by operation of other circuits on the chip .

    Despite all this it can often be  a very cost effective method of controlling power.

     

    MK

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  • I've done this (or similar things) often. You have to be careful that the digital output pins can cope with the current and, in addition, that the voltage drop at the current in question is OK. Digital output pins are often a little noisier than the supply and the voltage drop is often modulated a little by operation of other circuits on the chip .

    Despite all this it can often be  a very cost effective method of controlling power.

     

    MK

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