2 Replies Latest reply on Sep 12, 2019 10:37 AM by boco_4418431

    CYUSB3304  Downstream Issue


      ! !Hello,

      We have a design with the CYUSB3304-68LTXC

      We took the design from the Evaluation board and we used it with Nvidia TX2I processor , we built 2 prototypes and the boards worked properly with all 4 ports including the USB3.0 and we went to pre-production of 25 boards and now we are noticing some of the board don't have the downstream on any of the port.

      We can see The Suspend LED is On, until Linux boot and it  turned Off

      In Linux we can see the Hub but No other USB port  are seen

      We know the Chip is Alive

      Power_en is never Low ( No attempt) Always High

      No Over Current ,  High

      Vbus is Off

      We have 26.04MHZ

      Reset is High

      Mode Select to Default 11 (Default No Eprom)

      we have 1.2V OK


      Could you tell me what could prevent the Chip from Enabling the Power Switch to provide Vbus?

      I attached the schematic for  review.



        • 1. Re: CYUSB3304  Downstream Issue



          -Please check the bulk and decoupling capacitors on VDD_IO and AVDD12_x pins from Table 3 in the Application Note https://www.cypress.com/file/140751/download.

          -Please add a bulk capacitor of 1uF on VBUS on US port and 150uF on VBUS in the DS ports to maintain stable voltage under maximum load condition.

          - When you saw PWR_EN pulsing initially, did you see the same behavior on VBUS on the downstream ports?

          -Could you please connect the hub to a Windows host and check if the issue persists?

          -Currently, is the PWR_EN staying high all the time while OVRCURR also stays high when measured on the hub pins? Please send us the screenshot of the waveforms if possible.


          Best Regards,


          • 2. Re: CYUSB3304  Downstream Issue


            We actually have the design working.. We only had 2 boards with the issue.. We validated all 24 boards and all have successful link.

            On the new revision boards we will be adding more caps as recommended, for now we increased the value of the cap as recommended.

            Thank you for all your help and please consider this issue closed.


            Thank you again!