Input level conversion

rnielsen · Joined: 23 Sep 2003 Posts: 852 Location: Utah

I have a device that runs on 3.3V. It's output is feeding a device that is running on 5V. The 5V device's spec. sheet states that it's input is a Schmitt Trigger and needs a minimum of 4V to see a high level on it's input.

This might seem to be a simple one for some but my brain has turned to mush since I've been trouble-shooting this one for a while and finally realized what my problem was. I didn't realize the input needed to be so high. Does anybody have an easy idea of how to convert the 3.3V device's output to go higher than 4V?

Ronald

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

See my post on 3.3v to 5v level conversion in this thread:
http://www.ccsinfo.com/forum/viewtopic.php?t=23154

libor · Joined: 14 Dec 2004 Posts: 288 Location: Hungary

There's a very good summary on all these 3V-5V level issues, called 3V Tips and Tricks on the Microchip website.
3V Tips and Tricks

newguy · Joined: 24 Jun 2004 Posts: 1903

MAX3371. Bidirectional translation without the need for a 'direction' control input.

rnielsen · Joined: 23 Sep 2003 Posts: 852 Location: Utah

I tried out the MAX3371 and it works great. Tiny little buggers, though. I had to use a magnifying glass to see what I was doing.

Thanks for the tip.

Ronald