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TUSB4041I-Q1: The "GRSTZ" pin is high(3.3V) but the crystal is not oscillating.

Jeong Hoon Kim
Prodigy 20 points
Part Number: TUSB4041I-Q1

Our circuit is set up as follows.
And we will do host control using SMBus interface.
The "GRSTZ" pin is high(3.3V) but the crystal is not oscillating.
Also, SMBus communication cannot be performed from the host.
Please let us know what went wrong.

◇Pin status
・GRSTZ : 3.3V
・TEST_TRSTZ : 1.2V
・XI : 0.7V
・XO : 0.7V

◇HARD STRAP PIN setting
・SMBUSZ/SS_SUSPEND：Pulldown with 1KΩ（LOW：SMBUS Mode SELLECT)
・SCL/SMBCLK：Pullup with 2.2KΩ
・SDA/SMBDAT：Pullup with 2.2KΩ
・FULLPWRMGMTz/FULLAUTOz/SMBA1/SS_UP：Pullup with 1KΩ（HIGH：SMBUS ADDRESS1)
・GANGED/SMBA2/HS_UP：Pullup with 1KΩ（HIGH：SMBUS ADDRESS2)
・PWRCTL_POL：Floating（HIGH：ACTIVE HIGH)
・AUTOENz/HS_SUSPEND：Pulldown with 1KΩ
・TEST_TRSTZ : Floating

  • 0
    TI__Guru*** 146535 points

    Do you have 0.1uf cap on GRSTz?

    can you PD test_TRSTz pin?

    If still not working, can you take waveform on GRST, FULLPWRMGMTz and GANGed pin?

    regards

    Brian

  • 0 in reply to Brian Zhou
    Prodigy 20 points

    Do you have 0.1uf cap on GRSTz? Yes. But removing it doesn't solve the problem. 

    can you PD test_TRSTz pin? Improved to 0.42V after DP 4.7kohm.

    If still not working, can you take waveform on GRST, FULLPWRMGMTz and GANGed pin?

    Additional waveform :

    Question 1> Can SMBus communication be performed before crystal oscillation?

    Question 2> The 24MHz Crystal currently in use is as follows.
                         Will it be a problem with parts selection?
                         If there is a problem, we are considering applying the following items.


                <Current>

                - Part Name : NX3225SA-24.000MHz-STD-CQS-1
                - Load capacitance : 8pF
                - Equivalent resistance :100ohm
                - Frequency stability : 50ppm

               <Next>

                - Part Name : ECS-240-20-30B-AEN-TR
                - Load capacitance : 20pF
                - Equivalent resistance :30ohm
                - Frequency stability : 50ppm

  • +1 in reply to Jeong Hoon Kim
    TI__Guru*** 146535 points

    1: SMBus should has nothing to do with crystal'.

    2:what crystal you are using? ESR below 50ohm and lod cap s 12pf to 24pf/

      GRSTz  should be turn on 3ms after 3.3v and 1.1v stable.

    Regards

    Brian

  • 0 in reply to Brian Zhou
    Prodigy 20 points

    The issue was resolved by modifying the HW as follows.

    1. GRSTz pin controlled by MCU.

    2. Changed the crystal. (18pF, 40ohm, 100ppm)

    Regards

    Jeonghoon