3 Replies Latest reply on Mar 30, 2020 10:31 PM by SananyaM_56

    Can you recommend the lowest power USB hub?

    GeFu_3059156

      We are looking for lowest power USB hub with the following constraints:

       

      1x high speed upstream port

      1x high speed downstream port (removable)

      1x full speed downstream port (non-removable)

       

      We have looked at the datasheet for the CY7C65632/34 and see the following numbers

       

      1 active high speed port = 51.9mA (typ) @ 3.3V = 171mW

      Assume 85% efficient buck from 5V to 3.3  and power = 171/0.85 = 201mW

       

      Is this power affected by transmission duty cycle?

       

      We think we can save power by having external access to the core voltage. Is there a device like this????

       

      By example a competitors device has dual supply inputs to separate internal LDOs

      3.3V @ 25mA + 1.8V @ 24mA = 126mW

      Again, assuming 85% efficient buck from 5V total power = 126/0.85 = 147mW

       

      Does Cypress have something that will compete with this?

       

      Geoffrey

        • 1. Re: Can you recommend the lowest power USB hub?
          SananyaM_56

          Hi Geoffrey,

           

          HX2VL is our lowest power hub which we can recommend as per your requirements. Could you please explain what you are referring to as transmission duty cycle with respect to upstream USB bus?

          We dont have separate access for the core voltage in HX2VL and the active power consumption ideally is as per your calculations. However, please check the suspend current which should be give a power consumption of 3.3V * 0.786 mA = 2.6 mW. Since idle state power consumption is an important parameter for most hub applications, please let us know if that can suit your requirement.

           

          Best Regards,

          Sananya

          • 2. Re: Can you recommend the lowest power USB hub?
            GeFu_3059156

            Thank you for your quick response.

             

            In our case, operating power and not suspend power is our critical parameter. Our product which incorporates the hub needs to allow 8 hours of operation on a typical Android cellphone.

             

            By transmission duty cycle, I mean the percent of time transmitting data. We transmit MJPEG video, a 4ms burst every 16ms.

            I assume the power specified in the data sheet needs to be adjusted by the duty cycle to get average power. Is this true?

             

            We will but an eval board of the HX2VL and run some tests. Thank you.

            • 3. Re: Can you recommend the lowest power USB hub?
              SananyaM_56

              Hello,

               

              The operating power which we specify in the datasheet is actually measured on enumeration. So it does not take into account the transmission duty cycle but is the average power taken across three devices on attach only.

              Please let us know if you have any queries while using the eval board.

               

              Best Regards,

              Sananya