Page 1 of 1
3.3v->5v 7 signals
Posted: Tue Sep 29, 2020 5:08 pm
by arkadiusz.makarenko
Hi
Iam looking for advice.
I want to translate and buffer 7 signals from mpu to outside world. What should I use to do it? It is one way only from 3.3 to 5v.
Can I just use something like 74AHC244 8bit Buffer/Line Driver 3 state? If yes what should I do with unused one? Just leave it floating?
Re: 3.3v->5v 7 signals
Posted: Tue Sep 29, 2020 5:14 pm
by exxos
It depends exactly what your doing... as TTL inputs will accept 3.3V as a HI anyway...
Re: 3.3v->5v 7 signals
Posted: Tue Sep 29, 2020 6:22 pm
by arkadiusz.makarenko
exxos wrote: ↑Tue Sep 29, 2020 5:14 pm
It depends exactly what your doing... as TTL inputs will accept 3.3V as a HI anyway...
It is external signal which will be sent outside, maybe over the cables to external device. And I would like to protect mpu as well.
Re: 3.3v->5v 7 signals
Posted: Tue Sep 29, 2020 6:39 pm
by cmorley
74AHCT244 or 74AHCT541 work well. You can also use 74HCT.
Just tie the unused input to ground or 3v3.
Re: 3.3v->5v 7 signals
Posted: Tue Sep 29, 2020 6:54 pm
by arkadiusz.makarenko
cmorley wrote: ↑Tue Sep 29, 2020 6:39 pm
74AHCT244 or 74AHCT541 work well. You can also use 74HCT.
Just tie the unused input to ground or 3v3.
Thank you.
Lets see how it will work out.
Re: 3.3v->5v 7 signals
Posted: Wed Sep 30, 2020 12:31 am
by rpineau
Use a 74LVC244 with pull-up to 5V on the output (5V side).
It's a 3.3v device with 5V i/o support. I use it a lot of places exactly for this.
Rodolphe
Re: 3.3v->5v 7 signals
Posted: Wed Sep 30, 2020 6:10 am
by Smonson
I've been using 74AHCT245As for my VGA mod, since they only cost AUD 50c each and they do the job. If you only need a single-directional driver they work the same as the 244s (I just tie DIR to ground).