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TUSB8020B: Not read/write TUSB8020BIPHPR but the HUB keeps getting hot

Kevin Huang8
Genius 4515 points
Part Number: TUSB8020B

Tool/software:

Hi Team,

There is a heating problem when the load is light.
The HUB connects a USB3 (USB3 to EMMC) and a USB2 (LTE card) device

(1) When connected to USB3+USB2.0,
1V1 current consumption is 355mA
3V3 current consumption is 89mA

(2) When USB3 disconnects USB3 TX/RX + USB2.0, it is equivalent to both channels being USB2.0
1V1 current consumption is 69mA
3V3 current consumption is 54mA

In the above two situations, there is no access to the device (IDLE)
But the current consumption will not drop, and it is always at a high current consumption.

Why doesn't it change to low power mode? Please review schematics.

2475.TUSB8020BIPHPR.pdf

  • 0
    TI__Mastermind 38705 points

    Hi,

    I'm not sure I understand. When the USB3 and USB2.0 devices are connected are the functional?

    If they are both on and functioning the current draw is with expectation.

    In the above two situations, there is no access to the device (IDLE).

    What is the state the devices are in, are they in U0 or U1? 

  • 0 in reply to Vishesh Pithadiya
    Genius 4515 points

    Hi Vishesh,

    I'm not sure I understand. When the USB3 and USB2.0 devices are connected are the functional?

    • The device can work

    If they are both on and functioning the current draw is with expectation.

    In the above two situations, there is no access to the device (IDLE).

    • It's currently idle, but the hub current draw is at its maximum.

      When connected to USB3 and USB2,
      the 1V1 current draw is 355mA, and the 3V3 current draw is 89mA.

  • 0 in reply to Kevin Huang8
    TI__Mastermind 38705 points

    Hi Kevin,

    Kevin Huang8 said:

    I'm not sure I understand. When the USB3 and USB2.0 devices are connected are the functional?

    • The device can work

    If they are both on and functioning the current draw is with expectation.

    In the above two situations, there is no access to the device (IDLE).

    • It's currently idle, but the hub current draw is at its maximum.

      When connected to USB3 and USB2,
      the 1V1 current draw is 355mA, and the 3V3 current draw is 89mA.

    There are different states that will control the power draw of devices connected to the hub. When I ask what state are the are the devices in id not not have anything to do with data being transferred between the hub and the device. 

    USB3.2 has defined power states in sections 7.5.6 (U0), 7.5.7(U1), 7.5.8(U2), and 7.5.9(U3). I have attached a reference image here.

    We will focus on U0 as this is the state the devices are in from my understanding. 

    As per the spec, data does not need to be transferred to be in the U0 state. Even if there is no data being transferred, the devices can be in the U0 state. The host must transition into lower power states. We can track what state the bus is in using a protocol analyzer, but as the devices are functional its most likely that the devices are in U0. 

    The current consumption seems to be within spec.

    We can have a look at this register 0x05 and make sure we have low power levels enabled.