Hi Clewer,Brian (Clewer,Brian), in <35914910@tarkus> on Jun 24 you wrote:

> The data sheet does say that the voltage on any pin should be -0.6v to
> VDD+0.6v (and I guess it's because of the protection diodes, as you quite
> rightly say) BUT it also says that the open drain pin (RA4) only has
> protection diodes connected to VSS only!  Well, if this is true, I would
> think that the voltage on the open drain could go higher.
>
> Has anyone used this pin to control voltages above VDD ?

Some people on this list have previously pointed out that there maybe
exists a manufacturing test mode that is triggered by RA4= 14V.  You should
not violate the datasheet if you want to be on the safe side.