3 Replies Latest reply on Aug 21, 2020 2:27 AM by YatheeshK_36

    What are the power sequencing requirements for CY7C65211

    YvDe_4754711

      The FAQs mention that it is acceptable to apply VCCIO before VCC for CY7C65213:

      USB-Serial Bridge Controller FAQs - KBA224054

      Does this imply that for CY7C65211 it is ok to apply VCCIO before VBUS?

      We are considering to use the CY7C65211 in a battery-powered design with 1.8 V IO levels.

      We can only supply VBUS from the actual USB port (no other 3.3V or 5V source available),

      but could sequence VCCIO with respect to VBUS at best in software (so VCCIO starts a few ms after VBUS)

      or simply keep it on at all times (VCCIO is present when VBUS is not).

      Is either of those configurations acceptable as long as we ensure XRES is kept low until both rails are stable?

        • 1. Re: What are the power sequencing requirements for CY7C65211
          YatheeshK_36

          Hello,

           

          There is no power-on sequence requirement for USB-Serial devices (CY7C65211/213/215 and its corresponding A parts).

          So VCCIO/VDDD can be powered before VBUS.

           

          The VCCIO/VDDD will power the core logic and IOs, where as the VBUS will only power the USB PHY. Absence of VBUS will disable the pull-up on the DP line (no current will be drawn from the VBUS line).

          You can keep the VCCIO/VDDD powered all the time, provided that the current consumed by the core and IOs will not be a concern.

           

          Else, you can use a 3.3 V regulator on the board and use the VBUS line as input to the regulator and provide power to the VDDD/VCCIO when the VBUS is powered.

          Refer to the schematic design in CYUSBS234 DVK.

           

          Thanks,

          Yatheesh

          • 2. Re: What are the power sequencing requirements for CY7C65211
            YvDe_4754711

            Hey Yatheesh, thanks for the answer!

             

            What current consumption may I expect for the CY7C65211 with VCCIO active at 1.8 V and VBUS removed?

            The datasheet states 5 uA in USB Suspend (which would not be a concern), does that also apply for VBUS removed?

            Would I have to pull nXRES low to achieve that?

             

            Thanks,

            Yves

            • 3. Re: What are the power sequencing requirements for CY7C65211
              YatheeshK_36

              Hello,

               

              Yes, when the VBUS is not present and the suspend feature is enabled using the USB-Serial Configuration utility, the device will go to suspend mode and draws a typical of 5uA current. You can check if the device is in suspend mode by monitoring the SUSPEND pin of the USB-Serial Device.

               

              Thanks,

              Yatheesh