Say I used a diode going to 5v, wouldn't this bring the RA4 output down to about 5.6v. Where would I take the address line from? I need about 10v to go to the 4051. Anyway, I think I might use an open collector buffer. (i have three other outputs going to the 4051. I was going to use transistors for them.) I'll have to glue the buffer to the board as I've run out of space! Thanks, Stewart At 05:01 PM 5/07/99 +1000, you wrote: >Hi Stewart, >Could always use a series resistor and a zener >diode to ground or a normal diode to a 5v rail.. > >Regards >Peter Mcalpine >petermca@ozemail.com.au - www.ozemail.com.au/~petermca >mcalpine@gme.net.au - www.gme.net.au >www.wrx.org.au > > >----- Original Message ----- >From: Stewart Pye >To: >Sent: Monday, 5 July 1999 4:50 >Subject: Re: Open Drain Pullup > > >> All I could see in the data sheet said maximum 6V on all I/O pins too. >> What's the point of having an open drain output then? >> >> Stewart. >> >> >> >>ra.4 can be pulled as high as 14v iirc on the f84 part, should be fine, >> >>so long as your 12v supply doesn't spike or anything >> >> >> >> mark >> > >> >i am not saying mark is right or wrong here but i would ask for a second >> >opinion before doing something as drastic as this. i just had a quick >> >look at the specs to confirm my suspicion and i did not see anything off hand >> >that would suggest you can do this. iirc only the 17cxx parts have high >> >voltage >> >pins (and some new 16c5x family member in the future parts list.) >> > >> >jim >> > >> >>stewart pye wrote: >> >>> >> >>> hi.... >> >>> >> >>> i'm interfacing a 16f84 to a 4051 analog mux with a 12v supply. >> >>> is it safe to put a 10k pullup resistor to +12v from the open drain output >> >>> ra4?. >> >>> >> >>> thanks >> >>> stewart. >> >> >> >________________________________________ >> >email: newfound@pipeline.com.au >> >http://www.new-elect.com >> >warp-13 sale now on. $48usd with world delivery. >> >mplab compatible pic programmers and firmware >> >upgrades for many programmers. >> >________________________________________ >> > >