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TUSB8044: Input Clock Requirements

Kenji Ohno1
Genius 5095 points
Part Number: TUSB8044

Hi Team,

My customer would like to know about clock input.

Regarding the clock input, is there a specification of the minimum value maximum value of VH and VL?

The clock oscillator that my customers want to use is as follows.

Can they use it?

　VH min 90%VDD = 1.62V

　VL max 10%VDD = 0.18V

Also, is it necessary to pull down D + D -?

(In TUSB 2036, it was necessary to pull down with 15 KΩ for detection to D + D -)

Best Regards,

Kenji

  • 0
    TI__Guru 60865 points
    Hi Kenji,

    The only clock requirements are when using an external clock source such as an oscillator, the reference clock should have a ±100 PPM or
    better frequency stability and have less than 50-ps absolute peak to peak jitter or less than 25-ps peak to peak
    jitter after applying the USB 3.0 jitter transfer function. XI should be tied to the 1.8-V clock source and XO should
    be left floating. The customer's clock signal sounds acceptable.

    For the TUSB8044 it is not necessary to pull down the D+/D-, the pulldowns are integrated into the device.

    Regards,
    JMMN