1 Reply Latest reply on Aug 6, 2015 1:21 PM by DaKn_263916

    Simultaneous digital output at 5V and 3.3V levels?


      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. Re: Simultaneous digital output at 5V and 3.3V levels?

          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.