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TUSB8041: PWRCTL Polarity wrong ?

Part Number: TUSB8041


The data sheet describes quite clearly that the PWRCTL_POL pin must be pulled high to control Active High peripherals.

For security reasons I even have an additional 10k pullup to PWRCTL_POL.

When the linux kernel tries to activate the hub power, the port stays powerless.

After i tell uhubctl to turn off the power

uhubctl -a off -n 0451 -p 1 -R

The port gets powered on.

Is this a software or a hardware problem ?

  • Hi Christian,

    The hub power control outputs will be active high when PWRCTL_POL is pulled high.

    Please note when USB_VBUS is high,  the hub will not turn on downstream port power until the host sends the appropriate USB commands to do so.  If battery charging is enabled on the downstream ports (pullup on PWRCTLx/BATENx or through the hub register) then downstream port power is enabled when USB_VBUS is low, then toggles low when USB_VBUS goes high and waits until the host sends the appropriate USB commands.



  • It works. If i remove my external pullup and rely on the internal one.

    Whats wrong here ? Is pulling UP not allowed ?

  • Hi Christian,

    Can you probe the pin at power on?  I'm not having any trouble adding a pullup on the EVM.