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PSoC™ 5, 3 & 1 Forum Discussions

Level 2
Level 2
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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?



1 Reply
Level 9
Level 9
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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.