2 sets of bi-directional inputs and 1 output across 2 different voltages

So there is a chip I'm wanting fabricated that will be plugged into using edge connectors / gold fingers 2 completely different systems.

One system is 3.3v CMOS and it has one set of pinouts.

The other system is 5v TTL and it has a completely different set of required pinouts.

All I'm wanting is for one of the 2 sets of pinouts to be connected to the edge pins allowing for bi-directional traffic

When looking at multiplexers, assuming multiplexers are my solution, the problems I'm running into is

  • voltage differences
  • CMOS/TTL differences

While I'm wanting just a wire connecting the pins to one of two wires it instead determines on it's on whether it's a high or low based off of either CMOS or TTL and then gives the correct output which isn't what I want because one system will use CMOS and the other TTL and the multiplexer only goes off one system so I need it to just pipe the wire through.

Maybe theres another solution and multiplexers aren't it or maybe I need to do this with passive components and skip IC's. I'm not sure what to do but any help would be great.

It looks like this might do


But I'm still confused (From looking at the electrical specs and ratings) if it can handle and pass-through 3.3v and 5v data signals of CMOS and TTL.

So I'm still at a loss.

Is there any overlap in the used pins? Or are pins in system A, used for something else in system B?

Otherwise I would just use different pins for both and add a bidirectional level shifter for the system with the different voltage than your uC.

Unfortunately their totally different usages and purposes - I would want them to be isolated completely behind a switch.

I'm using resistor dividers to divide the voltage down to 3.3 from 5v but it still doesn't help with the TTL and CMOS specs.

Luckily TTL and CMOS isn't much of a problem with the uC and other components but it seems to be a problem with the multiplexers as the high and low are not aligning properly. The multiplexer data sheet is confusing because while it acts like there is a high and low voltage range it also says the 2 ends are directly connected and gives a general voltage range so I'm pretty confused as to whether it matters or not especially if the wires are directly connected.

I'm not sure if I should pursue the multiplexer solution but it seems like it's the best solution I've found and the one I posted earlier seems like a good one to use it's just the datasheet is confusing a bit as to whether it will work or not.