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TCA39416: Glitchy waveform was found on 2xTCA39416

William Hu
Prodigy 180 points

Part Number: TCA39416

Please refer to attached file,thanks.TCA39416.pptx 

  • 0
    TI__Mastermind 43610 points

    Hello William,

    Our I3C expert is out of office. He's returning back on Wednesday and help you answer your question. Thanks!

    Regards,

    Josh

  • 0
    TI__Guru 65568 points

    Hi William, 

    I assume that Pass 2 Topology is passing. 

    Pass 3 Topology is failing with the change of TCA39416 location. 

    Is bypassing the TCA39416 a workable solution, or is 1.0V to 1.8V level translation needed? 

    I am curious to know the BOM changes made to the series resistor, what resistances were tried in topology 3 that did not fix the issue? 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    Prodigy 180 points

    I3C LS Diagram_20261008.pdf

    On the DIMM side, we continuously observe approximately 22.2 kHz noise on the SDA signal, with an amplitude of around 160 mV. Based on the pulse width and waveform characteristics, I suspect this could be the output generated when the level shifter is being triggered.

    We observed continuous 45 kHz, 0.3 V noise on the SDA signal at the BMC side. Any suggestions? Thank you.

  • 0 in reply to William Hu
    TI__Guru 65568 points

    Hi William,

    William Hu said:
    On the DIMM side, we continuously observe approximately 22.2 kHz noise on the SDA signal, with an amplitude of around 160 mV. Based on the pulse width and waveform characteristics, I suspect this could be the output generated when the level shifter is being triggered.

    This looks like an ACK pulse by the DIMM. When the DIMM pulls SDA low, it pulls low with a different VOL than the host controller. 

    Check to see if this 160mV pulse is during the 9th clock SCL, this would indicate an ACK. 

    William Hu said:
    We observed continuous 45 kHz, 0.3 V noise on the SDA signal at the BMC side. Any suggestions? Thank you.

    This looks to be a periodic noise in the system influencing the TCA39416, but not the device itself. 

    Since VCC1 = 1.0V, the VRTA trigger is = 0.3 x 1.0V = 0.3V. This spike could potentially trigger the RTA it seems. 

    Is there any way to implement series resistors to the TCA39416 to help lessen this spike? 

    Regards,

    Tyler