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Original question:

TUSB8041: Port configuration and clock input

TUSB8041: Power management disable

Ben Strawbridge1
Prodigy 240 points
Part Number: TUSB8041

Hello,

I am doing a really simple hub implementation and want to use the minimum number of components. the design does not require any power control.

I am slightly unsure how to achieve this, particularly as the FULLPWRMGMTz pin seems to be defined in contradictory ways from the datasheet. it says in the same section that it has a pull down., that being low enables power switching and that leaving it unconnected disables power switching.

I/O, PD Full power management enable/SMBus address bit 1/SuperSpeed USB Connection Status
Upstream port.
The value of the pin is sampled at the de-assertion of reset to set the power switch control:
0 = Power Switching and over current inputs supported.
1= Power Switch and over current inputs not supported.
Full power management is the ability to control power to the downstream ports of the
TUSB8041A using PWRCTL[4:1]/BATEN[4:1].
When SMBus mode is enabled, this pin sets the value of the SMBus slave address bit 1.
Can be left unconnected if full power management and SMBus are not implemented.
After reset, this signal indicates the SuperSpeed USB connection status of the upstream port
if enabled through the stsOutputEn bit in the Additional Feature Configuration register. When
enabled a value of 1 indicates the upstream port is connected to a SuperSpeed USB capable
port.
Note: Power switching must be supported for battery charging applications

Please can you advise me the correct configuration for this pin (and any others i need to set) to disable power control on all pins?

thank you

  • 0
    TI__Guru 60870 points
    Hi Ben,

    Ah, looks like this line is a typo: "Can be left unconnected if full power management and SMBus are not implemented.". The previous gen of the hub had an internal pullup on this pin which is where the note came from, but the note doesn't apply to TUSB8041 which has a pulldown.

    Please install an external pullup for your application.

    Regards,
    JMMN
  • 0
    TI__Guru 64326 points
    Hi Ben,

    In addition this pin only changes the USB Hub descriptor reported by TUSB8041 to the USB Host. It does not impact functionality but may be needed for USB-IF CV testing.