Re: [uCsimm] Are the uCsimm I/O pins 5V Tolerant?

From: Geoffrey Wossum (
Date: Fri Feb 04 2000 - 00:38:29 EST

> I would stay away from LS as when a device is new it can be
> 'healthy' enough to go to 4.2 volts VoH. But you are correct, if you
> are interfacing 3.3v logic to +5 logic, use LS (or about anything but
> HC). If you really need to kludge a +5 to 3.3v interface between LS and
> 3.3 logic, why not build a resistor totem and pick off at the lower
> resistor, example:

All right. Tracking down (small quantity) suppliers of LVX series chips
is next to impossible. However, LCX series is easy to get, and it looks
like it would do the job. Whereas the LVX actually has dual 3.3/5 V
supplies and level shifts, the LCX is 3.3 chip that is 5V tolerant and
just keeps 5 volts from getting through to the 3.3 side.

Does anyone have a opinion or experience either way on using LCX chips for

Geoffrey Wossum
Project AKO -
Internet Imperialists -

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