In my ultracpu board I have a 74ls14 schmitt trigger to read signals from a potentially noisy bus and give them as inputs to a CPLD that is 5V tolerant.
https://github.com/fachat/csa_ultracpu/ ... -sch-1.png

I now want to move to a 3.3V only CPLD, but the bus will still be 5V, so I need level translators - but still reading from a noisy bus.

The best I have come up with is a 74lvx4245 that has 8 level translators - but a much larger footprint. Alternatively I could us a 5V 74ls14 and a 3.3V 74lvc06(the 5v tolerant one) but that does not save much footprint I guess. Similar having to solder multiple resistor based voltage dividers isn't much fun.

It's not that I couldn't use one of the additional translators (of the 74lvx4245, for one other signal on another sheet) , but I would be happy if there would be a solution with a smaller footprint.

Any ideas?

Many thanks
André

_________________
Author of the GeckOS multitasking operating system, the usb65 stack, designer of the Micro-PET and many more 6502 content: http://6502.org/users/andre/

A CMOS part like 74HC14?

Edit: Never mind. Max input voltage is limited to Vcc+ 0.5

There is this:

http://www.johnhearfield.com/Eng/Schmitt.htm

74LVC14A ?

https://assets.nexperia.com/documents/d ... LVC14A.pdf

I have had a look at this too, but using it with 3.3V moves the Schmitt Trigger trigger levels down too. So it accepts 5V but switches at differen voltages on the bus - changes characteristics and I don't want that. For example ...

Meh. Ignore that..

Looking at the datasheet again it seems I have had a wrong look before... it looks like the trigger voltages at 3-3.6V supply are exactly right for 5V TTL (0.8V for going down, 2V for going up)

Crazy I missed this, I was probably looking at the 74lv14 instead. I'll have a thorough second look!

Many thanks for that!

_________________
Author of the GeckOS multitasking operating system, the usb65 stack, designer of the Micro-PET and many more 6502 content: http://6502.org/users/andre/