pic microcontroller discussion list wrote:
>
> Lets try some lateral thinking.
> Why is this a 3R9?

I don't know since I did not design the circuit :)

however:

> It MAY be a surge protector to protect following circuitry.

that's my thinking, too.

> It doesn't have much voltage drop across it in normal operation.
> If it is feeding a regulator and voltage drop doesn't matter why not
> increase its value?
>

Unfortunately it can't be much bigger due to dissipation under worst
case conditions. I do not have the source code, flow-chart, nor data
sheets for all of the components. Not sure how they expect me to be
of much help if they withhold that information.

>
> These people make "pulse resisting" versions (0805 and larger) and the
> graphs suggest you want a larger part :-(
>
>     http://www.irctt.com/pdf_files/PWCAPPLICATIONNOTE.pdf
>

intersting. thanks for the link.


Phil Eisermann
Electronics Engineer
The Ridge Tool Company
(440)329-4680

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