I'll have to look into that (transorbs).  I have 12V fed to an 8V=20
regulator then a 5V regulator.  Considering they're not LDO's (~2V=20
overhead voltage), I have considered that could be an issue.  The 8V is=20
no longer required on the board, so that will be eliminated in the next=20
revision, but I'm also changing to a switching regulator.

Cheers,
-Neil.



On 11/18/2014 6:00 PM, Jasdip (Paul Owen) wrote:
> Had a similar problem with an 8V field bus supplying a PIC via a linear 5=
V
> regulator.
> When the 8V field bus had a partial short, it dropped the line voltage to=
 3
> or 4V.(Current limited over a long line)
> When the field partial short was remove, the linear regulator which was
> driving hard
> to maintain voltage, let a spike of high voltage through before it could
> regulate properly.
> This was corrupting the EEPROM on the PIC but did not affect the flash. A=
 5V
> transorb across the PIC fixed the problem.
>
> Paul
>
>

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