2 Replies Latest reply on Apr 25, 2020 3:00 PM by ViGa_4685546

    Issues with CY8C9520A-24

    ViGa_4685546

      Hello,

       

      We are using a CY8C9520A-24 on one of our boards and we have several issues with it.

       

      When we try to set the Port0 Bit6 from 0 to 1 the component is rebooting and every GPIO comes back in the default configuration set in the EEPROM. On our board, this pin is driving 3 enable pins from 3 LDOs. These pins only require a few µA to be driven, we are far from the current limit of the CY8C9520. We even tried to switch all the other GPIOs of the component to High-Z, to be certain that other pins were not consumming any current but the result is still the same.

       

      Here is the schematic of the parts involved in this problem:

      CY8C9520A issue.png

      Do you have any clue on what could happen here? What could cause the component to reboot?


      Kind regards,

       

      Victor

        • 1. Re: Issues with CY8C9520A-24
          SampathS_11

          Hello,

           

          1. It seems like there is a dip in the VCC_SENSORS when the three voltage regulators are switched on. To check if this is really the root cause, the regulators can be removed one by one. In case all the regulators are removed, and the reset issue still happens, the root cause can be deemed to be different.
          2. Very narrow spikes on the EXPANDER_RESET can also cause this issue. A n RC filter can be used to eliminate these narrow spikes. The RC can be set to a time constant of around a ball park figure of one fifth the active pulse width on this line. A resistor of 1k is recommended. The C can be selected according to the time constant chosen.

           

          I do not have information about the source of VCC_SENSORS and EXPANDER_RESET. Hence, I am unable to figure out any further causes. Do kindly let me know after you have eliminated the above two root causes.

           

          Best regards,

          Sampath Selvaraj

          • 2. Re: Issues with CY8C9520A-24
            ViGa_4685546

            Hello,

             

            Thank you for your answer, it was really helpful.

            We indeed noticed a dip on VCC_SENSORS which is powering the CYC9520A. It was caused by the voltage regulators which caused a current spike during their activation. The problem is now solved!

             

            Kind regards,

             

            Victor