1 Reply Latest reply on Nov 9, 2020 3:33 AM by RashiV_61

    CX3 - routing through DNU pads

    NiCo_4789341

      Hello,

       

      I am trying to optimize the physical layout of a CYUSB3065 on a 4-layer PCB.
      In the datasheet there are several balls marked as DNU
      (F1, F7, F8, F9, F10, G7, G8, G9, G10, H2, H3, H7, H9, H10, J1, J2, J3, J4, J10, K1, K2, K9, K10, K11, L10).

       

      I was wondering if it is possible to connect them to other signals in order to pass through them when routing traces.

       

      In other words, shall ALL these pads remain strictly unconnected? Maybe a subset can be freely connected?

       

      Secondly, is it possible to take advantage of this approach with unused GPIO pads?

      I suppose all unconfigured GPIOs will stay high-impedance during all stages (power-on, boot, run) or must I expect spurious transitions?

       

      Thank you,

      Nicola.

        • 1. Re: CX3 - routing through DNU pads
          RashiV_61

          Hello Nicola,

           

          Please do not connect any other pins which marked as DNU.

           

          In other words, shall ALL these pads remain strictly unconnected? Maybe a subset can be freely connected?

          >> Please do not connect any other signals to the pins which are marked as DNU.

           

          I suppose all unconfigured GPIOs will stay high-impedance during all stages (power-on, boot, run), or must I expect spurious transitions?

          >> Please refer to section 11 of the application note AN76405 https://www.cypress.com/file/201991/download  which mentions the default states of the GPIO's of FX3. Similarly, for CX3 the GPIO state might differ based on the boot option. Please try probing the GPIO's for the default state  (while in bootloader mode)

           

          Please let me know which kind of signals are you trying to pass through the unused GPIOs

           

          Regards,

          Rashi