Hello everyone,
     Another thing to look for is a bad diode in the alternator. The=20
batteries would still charge up because most tractor trailers are driven=20
for extended periods of time. There should would be a lot of noise on=20
the electrical system. But still the board needs some high value caps on=20
it. You can get 25 volt 2200uFD caps that are relatively small.
Thanks,
rich!

On 10/28/2014 3:26 PM, James Cameron wrote:
> I would scope the PIC and external EEPROM Vdd pins and watch what
> happens under various durations of power loss.
>
> If the pin and power budget allows, power the external EEPROM from an
> I/O pin, to ensure it meets any minimum off time spec.
>
> (in the product that takes most of my time, several devices needed
> discharge clamps so that we could meet their power down specs.  just
> turning off the bus wasn't enough, we also had to pull it down.)
>

--=20
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