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TUSB7340 High power consumption in "System on - device idle" state

Johannes Winkler84
Prodigy 30 points
Other Parts Discussed in Thread: TUSB7340

Hello @ all,

i'm using the TUSB7340 in the quite same design as in the EVM Demo-Board.

But when i switch on the power supply, the board will consume 850 mA at 5 V. Further more the TUSB7340 gets very hot.

I think it could be the same problem from the post: e2e.ti.com/.../365370

But unfortunately there is no solution at the end of the post.

Can you help me?

Which informations do you need?

Here is the schematic:


Thank you in advance!

Best regards,

Johannes

  • 0
    Prodigy 30 points

    Sorry, here the schematic:

  • 0 in reply to Johannes Winkler84
    TI__Guru* 76130 points
    Hello,

    You say it is drawing 850mA from 5V, can you measure how much is drawing from the 3.3V and 1.1V voltage regulators?
    Is the thermal pad properly grounded?
    Remove the resistor R8, most of the PCIe transmitter already incorporates the terminations on PCIE_REFCLK.
    As mentioned in the post you brought to attention: are WAKE# and/or CLKREQ# oscillating?
    Does it make difference if you connect a USB device?

    Regards
  • 0 in reply to Elias Villegas M.
    Prodigy 30 points

    Hi,

    thank you for your reply.

    I switched off the LDO for 1.1V and then the measured current was about 430mA. So a big amount of the power is consumed by the 1.1V section. Further more the LDO for 1.1V gets hotter than the LDO for 3.3V.

    I removed the resistor R8 but nothing changed. At the WAKE# Pin and the CLKREQ# Pin are no oscillations measurable. And it makes also no difference if you connect any USB device.

    The thermal pad is also grounded properly. (See attached picture, the blue layer is Ground)

    Could you please tell me the solution of the problem of that post i brought to attention? (if there was one)


    Thank you!

    Regards

    Johannes

  • 0 in reply to Johannes Winkler84
    Prodigy 20 points
    Hi Johannes,

    I'm facing the same problem with the 7320 so I wonder if you were able to find the cause of your problem. If you were able to resolve the problem, could you explain how you were able to fix it and what was the cause.

    Thanks, you're help would be appreciated

    Christian