> I've wondered recently how much protection you can gain by "chaining"
> 78xx regulators.  For instance, for the "typical" 5V project from a 12V
> car supply, you might use a 7509 regulator to get from 12 to 9V, and a
7805
> to get from 9 to 5V, or something similar.  Also has the advantage of
> spreading out your power dissipation.  Similar tricks could be played with
> multiple lm317 type regulators...

I'm not sure how much extra "protection" this affords, although it would
spread the power dissipation.  A 50 or 100 volt spike will still fry
something.  Also, this scheme will increase the quiescent current, although
that's not an issue if the device is off when the car is off.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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