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Simultaneous digital output at 5V and 3.3V levels? | Cypress Semiconductor

Simultaneous digital output at 5V and 3.3V levels?

Summary: 1 Reply, Latest post by danaaknight on 06 Aug 2015 01:17 PM PDT
Verified Answers: 1
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darioringach's picture
15 posts

I have a project with a PSoC 5LP interfacing with both 5V and 3.3V external components.  

Is there a way to have two different output pins connected to a single digital line, one with 5V and another at 3.3V levels?

Or do I need to level shift outside of the chip?



user_14586677's picture
7646 posts

You can set an I/O domain to either 3.3V or 5V or whatever externally.


1) You could use external MOSFETs to switch the I/O domain levels under program



2) You could use a 3'rd output, open drain, and a zener to clamp a 5V pin to 3.3V at the

pin. You would have to evaluate current draw but should be OK. Also noise margin for

logic 1 level when clamp in effect, eg. zener tolerance.....


3) You could use an open drain and a V divider scheme, switch the leg to ground to effect the

3.3. Evaluate speed, rise time issues would be prudent.


4) If speed not an issue use a PGA and change its gain level

with appropriate API.


Some ways of doing it.


Regards, Dana.

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