I bet +8.5V is more that enough for a logic 1 for a 9V 4017.  Use a 1K
pull up and a 15k pull down.  That will give you 8.4V for a logic 1 and
the PIC cal pull a logic 0.

Sherpa Doug

> -----Original Message-----
> From: Byron A Jeff [mailto:byron@CC.GATECH.EDU]
> Sent: Wednesday, October 24, 2001 6:31 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [PIC]: Need advice on using the Open-collector output
>
>
> On Wed, Oct 24, 2001 at 05:21:51PM -0400, Olin Lathrop wrote:
> > > But will putting 9V
> > > into the open-collector output cause problems?
> >
> > Read the data sheet.  The maximum voltage for the open
> drain output is well
> > specified.
>
> Just took a quick peek at the 16F87X page. 8.5V max. Looks
> like you'll need
> a transistor. Also 7407 buffers and 7406 inverters (both OC)
> are rated up to
> 30V.
>
> Hope that helps,
>
> BAJ
>
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