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Topic: 7805 voltage regulator help (Read 862 times) previous topic - next topic

MarkT


Hey folks,

I have a 36v battery that i need to use to power my arduino fio.  I'm trying to use a 7805 voltage regulator to bring the voltage down to an acceptable voltage for the arduino to regulate (<12).


Well that could be an expensive mistake - the absolute maximum rating for a 7805 input voltage is 35V.   You would do much better to use a DC->DC converter - far less power wasted / heat generated too.
[ I won't respond to messages, use the forum please ]

jboncek

Thanks for all the input folks.  I missed a day here cause I forgot to hit notify for replies.

1 important detail for some of the responses:  I'm using a Fio, which runs on 3.3v.  Primarily for its size and ease if use with an xbee.

But that aside, I still need a 5v power source for the rest of the system. 

From the responses, however, I would imagine the 7805 is the going into a thermal shutdown state, when current is applied.  Without load it puts out a steady 4.95vdc.

Right?

I guess I'll look into a Dc to DC converter as jwatte and dan mentions.

Thanks.

jboncek

For those who find this thread after me, I just ordered this dc-dc switching regulator. We'll see how it performs.

http://www.digikey.com/product-detail/en/R-78C5.0-1.0/945-1395-5-ND/2652148

And in truth, it's not really a 36v supply, it's 39 fully charged.

zoomkat

Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   8)

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