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AM5726: Transitioning from USB 2.0 to USB 1 Interface

Daniel Cheng1
Mastermind 8215 points

Part Number: AM5726

Hi Expert,

 

We are transitioning our interface from USB 2.0 to USB 1. In the original design, USB1_DRVVBUS had a pull-down resistor, whereas USB2_DRVVBUS did not. Is a pull-down resistor required after the modification?

Additionally, since we are not utilizing USB 3.0, is it acceptable to leave all unused signals floating?

orignal:

or.png

 

after:

after.png

Thanks!

 

Daniel

  • 0
    TI__Guru 56965 points

    The USB3 signals can be left floating.  The pull-down resistor ensures the default state of the IO.  For USB, the DRVVBUS signal should default to low to ensure VBUS is not applied without cause.  If using USB2_DRVVBUS, then yes recommendation is to add pull-down.