AVR-Chat

Thanks, I know exactly what you're talking about.  However, for
someone who might inadvertantly connect a +12V supply to the pin... It
would obviously try to sink lots of current through the diode, likely
blowing it up, then blowing up the MCU.  Would the effectiveness be
reduced by putting series resistors (say, 1k?) with the two diodes?

Or if the supply was connected backwards, all the current would try to
go through both diodes....  Trying to create an idiot proof box, but
you know how that goes.  ;)

Ryan



--- In AVR-Chat@yahoogroups.com, Ken Arck <ah6le@...> wrote:
>
> At 10:38 PM 7/8/2006 -0000, you wrote: 
> 
> I need to protect an analog input for an AVR.  Protect it from ESD,
> users connecting it wrong (i.e. to 12V power), etc.  Any suggestions
> on what to use?  Unity gain opamp?  "transorb" or similar transient
> device???  Discussion welcome.  Thanks,
> 
> <---Some expouse using zeners and currentl limiting resistors but I've
> always found the leakage current to be an issue. So now I use regular
> diodes to ground and the Vcc rail. See the attached schematic. The
diodes
> are general purpose silicon like 1N914 or 1N4148.
> 
> Ken
> 
>   ----------
> 
> 
>
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