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TUSB4020 Hub with TPS2052 switch

Amine Jebali
Prodigy 20 points
Other Parts Discussed in Thread: TUSB2036, TPS2042, TPS2052

Hello,

I am designing a 2-port USB hub using the TUSB4020. I successfully used the TUSB2036 before but our new application requires a USB 2.0 hub.

I followed the datasheet design recommendations and got the TUSB4020 to connect to my PC, it is recognized as USB 2.0 MTT Hub. However, I seem to have a problem with downstream ports.

I tried two different switches: the TPS2042 and TPS2052, changing the PWRCTL_POL pin to active low and active high respectively,

I noticed that the PWRCTL2/BATEN pins are always pulled high ( 3.3V ), regardless of PWRCTL_POL .

I attached my schematics for your reference. I appreciate any idea or help in identifying the source of the problem.

  • 0
    TI__Guru* 76130 points
    Hello,
    I guess you are only populating one resistor on PWRCTL_POL, am I right?
    Can you remove the pull-downs and edge control capacitors installed on DP1/DM/ and DP2/DM2?
    Regards
  • 0 in reply to Elias Villegas M.
    Prodigy 20 points

    Hello Elias,

    Thanks for the reply.

    Yes I am using one resistor to pull up/down the WRCTL_POL.

    I initially tested the hub without the the pull-downs and edge control capacitors installed on DP1/DM/ and DP2/DM2, then added them when it didn't work.

    I also added two 22uF caps on the TPS2052 OUT1 pin and changed the cap on the Hub reset pin to 1uF. Now the Hub works but intermittently. I would say that it works most of the time but sometimes the hub connects to computer but downstream devices does not, some random other times neither connects.

    I am going to scope the reset pin and power pins to see if I meet the timing requirements, in the meantime, if you have faced a similar problem , please let me know

    Regards,

    Amine