Hi Jacob,

> >> One of the advantages of an O/C (or Open Drain) output is that you can
 switch
> >>  between Gnd and a voltage higher than Vcc.
>
> >Woah boy.  Just remember that you are not talking about a ULN2003 relay
> driver here.  The PIC16C/F84(A) could be inadvertently be put into
> Probramming mode if you pull the _MCLR pin too high (especially
> when Vcc is low)  If you must have a 6V open collector output
> from say a set of batteries and you know that you chip will
> reset correctly (open collector reset IC connected to _MCLR then
> you can probably get away with it even if you put a low drop regulator
> onto the rest of the IC and run it at 5V.
>
> >If you want open collector at above supply voltage then put in the
> transistor and resistor and feel safe.
>
> >Cheers
> >Kalle Pihlajasaari     kalle@data.co.za
>
> What are you talking about? We are discussing RA4 here, not _MCLR...

My mistake, not at my most lucid when I posted the message.

There should be no direct side effects from using RA4 above supply
withing the limits of the spec (which is woefully unclear on this
point).

Cheers
--
Kalle Pihlajasaari     kalle@data.co.za
Interface Products     Box 15775, Doornfontein, 2028, South Africa
+27 (11) 402-7750      Fax: +27 (11) 402-7751