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TUSB4020BI: some questions

Hirotaka Matsumoto
Guru 27585 points
Part Number: TUSB4020BI

Hi all

Would you mind if we ask TUSB4020BI?

<Question1>
How long is the operation time for GRSTz?(XXus?)
After GRSTz is low, how long does device need to re-start?(zero start?)

<Question2>
Before settings are reflected, when there is access from other USB(BIOS), what kind of problem does it occur?
Of course, we think it will occur the problem which can't expect. 

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Expert 7395 points
    Matsumoto-san,

    After de-asserting GRSTz, the device will load the configuration settings and only after that, the TUSB4020BI will enable its receiver terminations so it can be enumerated by the system. Before setting are reflected, the TUSB4020BI will appear as disconnected and the Host Controller would not attempt any communication with it as per the USB specification, so no issues are expected.

    Enumeration timing would depend on many different factors like the method used to load the device configuration (external EEPROM, SMBUS master or default configuration by not having any of the other two), the operating system or host controller driver, the system resources, etc.

    Regards,
    Jorge