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AM5706: How to handle USBx_DRVVBUS

O.H
Mastermind 6400 points
Part Number: AM5706
Other Parts Discussed in Thread: TUSB8020B, TMDSEVM572X, AM5708

Hi experts,

Currently, my customer is starting to design a circuit that combines AM5706 and TUSB8020B.

Q:Do I need to make the same connection between USB1_RDVVBUS of AM5708 and USB_VBUS of TUSB8020B as TMDSEVM572X?

In this time, we are using USBHub (TUSB8020BIPHP), and the circuit is designed to control VBUS power supply by PWRCTL1/BATEN1 and PWRCTL2/BATEN2 of USB8020BIPHP. The USB1_DRVVBUS port of the SoC is recognized as a port to turn on/off the VBUS power supply, but since it is controlled by the HUB, it is treated as an unused pin.

When I checked the points about USB hub in "AM57x Schematic Checklist (Rev. B)", I found "USBx_DRVVBUS should be unconnected". I am confused because there is a difference between this and TMDSEVM572X. I would appreciate it if you could tell me the correct way to connect.

Best regards,
O.H

  • +1
    TI__Expert 4015 points

    You should follow the EVM schematic if possible.  The EVM schematic matches the USB Hub's upstream port design recommendation regarding VBUS.  Just make sure that the IO power supply governing USB_DRVVBUS is 3.3V, not 1.8V.  As for what the schematic checklist recommends, I can look into that in more detail.  It seems to be proposing a different arrangement for VBUS, which might also work, but I'm not sure what it would be.  Let me know if this answers your question.