5 Replies Latest reply on Nov 26, 2020 4:39 AM by SananyaM_56

    HX3 Downstream USB 3.0 to Type-C Receptacle

    ChKi_4789686

      Hello,

       

      I'm currently working on a USB Hub design that requires 2 downstream USB 3.0 ports (1 Type-A receptacle and 1 Type-C receptacle). I've been looking at using the HX3 family, since it seems to have all of the functionality I need. However, I need help on the SS lines for the downstream port of the Type-C receptacle.

       

      Given that it is a Type-C receptacle, the receptacle would require SS data connections for both orientations; however, the hub controller only has a single set of SS data lines for each port. I saw a high speed MUX being used in the HX3C USB Type-C Dock Reference design to resolve this issue, but I'd like to avoid using a MUX if possible.

       

      In the AN96527 Application Note (Designing USB Type-C Products Using Cypress's CCG1 Controllers), I found the segment below, which mentions that you can route the SS lines of Ports 1 and 2 to a single downstream Type-C connector which would resolve my issue above; however, I wasn't sure if this was possible since this is the only information I've found regarding this.

       

      Some questions:

      1. Does this implementation require the Shared Link technology mentioned (so only parts CYUSB3326 AND CYUSB3328)?
      2. Can the USB 2.0 data lines be connected from either port 1 or port 2 to the Type-C receptacle?
      3. If the other USB 2.0 data line (connected to audio codec in the figure below) is unused, can it be left floating?
      4. When paired with a CCG3PA PD Port Controller, can the 2.0 data lines route directly to the HX3 downstream port for legacy charging enumeration and feedback the devices required charging protocol to the CCG3PA via I2C?
      5. Is there a reference design for or similar to the below implementation?

       

       

       

      Thanks in advance!

       

      Best regards,

      Chris

        • 1. Re: HX3 Downstream USB 3.0 to Type-C Receptacle
          SananyaM_56

          Hello Chris,

           

          Yes, as you mentioned, the orientation would have to be detected to route the correct set of SS lines to the hub. For the orientation detection through a MUX using CC lines, you would require an external PD controller.

          1. No, the Shared Link feature would allow the USB 3.0 and 2.0 lines to be routed separately with VBUS control and is usually used when two different devices are connected to the USB 3.0 and 2.0 lines. If you are not connecting the audio codec to port 1 and routing both the USB 3.0 and 2.0 lines to the same Type-C connector which would connect to one device, it wont be necessary.

          2. Yes, either port can be connected since the USB 2.0 lines from the Type-C connector will be shorted together.

          3. Yes, if they are unused the lines can be left floating.

          4. If the USB 2.0 lines are connected to the hub, the hub itself is capable of BC1.2, Apple charging and can set the required mode based on the terminations on DP/DM. If you would like the hub to notify the charging mode to CCG3PA, the hub firmware would have to be modified to communicate it through I2C, which is not possible due to HX3 being a fixed firmware part. Additionally, you could use a mux to switch the lines between the hub and CCG3PA for any additional charging protocols (QC 4.0, AFC) which are only supported by CCG3PA.

          5. The reference design from the App Note that you are referring to is the only example we have of this implementation.

           

          Best Regards,
          Sananya

          • 2. Re: HX3 Downstream USB 3.0 to Type-C Receptacle
            ChKi_4789686

            Hello Sananya,

             

            Thank you for your response, it's very helpful.

            In regards to your response to Q4, I recall in one of the reference designs that I've seen where the USB 2.0 data lines were connected to both the CCG3PA and the HX3, but routed with minimal stubs to maintain signal integrity. Would you recommend doing this or as you mentioned, using a mux to switch the lines between the hub and the CCG3PA?

             

            Also, could you please recommend a USB Hub controller for the above USB hub design that would work well with the implementation below found in the CYPD3196 datasheet?

             

            Thank you!

             

            Best regards,

            Chris

            • 3. Re: HX3 Downstream USB 3.0 to Type-C Receptacle
              SananyaM_56

              Hello Chris,

               

              If the reference design is for CCG3PA automotive application, please contact the Sales office for more details and we can check the feasibility over a Tech Support case. I was recommending using a mux because if the two are connected, only CDP charging mode would work. Please refer to the KBA for more details- CCG3PA Hardware and Software FAQs - KBA231523

              Please also note that HX3 charging modes would have to be disabled so that both CCG3PA and HX3 dont enable BC 1.2 charging on the device.

               

              For the implementation shown, you could refer to HX2VL, particularly the 2-port part CY7C65634 which would provide two ports from the upstream DP/DM lines for the two Type-C connectors. But the I2C lines are only used for booting up from external EEPROM and since HX2VL is also a fixed firmware part, you wont be able to modify the firmware to support any custom configuration through the I2C interface.

               

              Best Regards,
              Sananya

              • 4. Re: HX3 Downstream USB 3.0 to Type-C Receptacle
                ChKi_4789686

                Thank you for the links, they're very helpful. So, to clarify a little bit more about the implementation of both USB 2.0 data and legacy charging protocols on the CCG3PA, I could go with one of the two options:

                 

                1. Route Dp and Dm lines to both the CCG3PA as well as one of the HX3 downstream port pin pairs with minimal stubs. In this case, the only legacy charging protocol that would be retained is BC 1.2 CDP.
                2. Use a mux to switch between the HX3 and CCG3PA and retain all legacy charging protocols: BC 1.2, QC, Apple Charging and AFC.

                 

                Is this correct? If this is the case, do you have an automotive grade mux that you could recommend for this application? Also, would the switching of the mux be controlled by one of the CCG3PA gpio ports considering the HX3 is fixed firmware?

                 

                Best regards,

                Chris

                • 5. Re: HX3 Downstream USB 3.0 to Type-C Receptacle
                  SananyaM_56

                  Hello Chris,

                   

                  Yes, your understanding is correct. The mux would allow you to switch the DP/DM lines based on whether you want to use them for data or legacy charging, and connect to either HX3 or CCG3PA accordingly. Please take a look at TS3USB221A-Q1, we dont have any USB 2.0 multiplexers. The mux switching could be done through CCG3PA GPIOs based on your required logic.

                   

                  Best Regards,
                  Sananya