3 Replies Latest reply on Apr 14, 2020 11:34 PM by VasanthR_91

    Why does ILR Switch drop the voltage ?

    Khaz_4682641

      Hi everyone,

      • I'm using cy8ckit-062-ble Cypress chip,And I'm working on ModusToolbox IDE.
      • I'm trying to generate a DAC signal on four GPIO pins and switching each one of these pins between Zero and DAC output,
      • So I tried to get out the DAC signal on these four pins directly form the Device Configurator but it does not work because the voltage of DAC drops (because it is effected with the resistors on my circuit and I cannot switching between Zero and DAC output signal).
      • So I decided to use the internal Op-amp as a voltage follower.
      • Here is schematic of the Op-amp

      • Here I'm using Op-amp0 and I'm trying to get out the Op-amp output signal on PIN0,PIN1,PIN2 and PIN6.
      • I have no problem of using PIN1 and PIN2 and controlling them from D81 switch and A11 switch.
      • But there are a problem of using PIN0 and PIN6 which are controlled from A20 switch, A30 switch and there common ILR switch.
      • When I'm trying to measure the output voltage on PIN0 or PIN6, There are a voltage drop on them.

      I don't know why there are a voltage drop on them, Is that because I'm using ILR switch? If true then why ?

       

      I'm sorry for my bad English .

       

      Regards,

      Khalil Azouz

        • 1. Re: Why does ILR Switch drop the voltage ?
          VasanthR_91

          Hi Khalil,

           

          For the PSoC 6 opamp the output can be directly connected to a pin and/or routed to an internal load using the analog routing fabric. The drive strength is selectable as either 10x or 1x. Connections to GPIO pins require the 10x setting. OA0s 10x output is directly connected to pin2. That is the pin recommended to be used when routing the OA0 to an output pin. In case you need the connect the output to some other pins, you can use the AMUX bus for the purpose with expected shortcomings due  routing and switch resistances.

           

          Best Regards,
          Vasanth

          • 2. Re: Why does ILR Switch drop the voltage ?
            Khaz_4682641

            Hi Vasanth,

            Thank you for replay,

            I really use AMUX bus for connecting the output to multiple pins, but there is a voltage drop on the op-amp output.

            when I connect the op-amp output to the AMUX bus there is no voltage drop, but when i connect the other pins to the bus the voltage drops immediately.

             

            Regards,

            Khalil Azouz

            • 3. Re: Why does ILR Switch drop the voltage ?
              VasanthR_91

              Hi Khalil,

               

              As I said and if you see the routing diagram again pin2 is supposed to be used as the output of opamp. The 10x driver output is directly routed to this pin. Trying to use other pins using the mux will have the disadvantages for the voltage drop. But if you use the opamp buffer before muxing , the output should be better compared to directly routing the output out of the DAC. Pin2 will always have to be used in this case as you are tapping the same output to other pin.

               

              Best Regards,
              Vasanth