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TLIN2029A-Q1: How to measure the VHYS?

Yoshikazu Kawasaki
Intellectual 851 points
Part Number: TLIN2029A-Q1

Tool/software:

Hello,

My customer is wondering how they can measure the VHYS of TLIN2029A-Q!?  The datasheet says Figure 8-4 and Figure 8-3, but the link gives Figure 6-4 and Figure 6-3 respectively.  I suppose the description is the datasheet should be Figure 6-3 only.  Would you please tell me how to measure that?

Best Regards,

Yoshikazu Kawasaki

  • 0
    TI__Mastermind 27690 points

    Hi Kawasaki-san,

    This seems to be a bug when revising the datasheet, it's linking to the correct figure 6-3, 6-4 in current datasheet, but the "figure 8-3, 8-4" here were not changed from the old datasheet. Thanks for letting us know.

    Regards,

    Sean

  • 0 in reply to Sean Guo
    Intellectual 851 points

    Hello Sean-san,

    Thank you for your comments.  I visited the customer and asked the background of the question.  They said it's difficult to meet the VHYS of 0.175Vsup as maximum value.  Wouldn't it be a typo?  It should be 0.175Vsup minimum since the current datasheet can say VHYS=0V is in the spec which shouldn't be true as hysteresis voltage.  Am I correct?  If the datasheet is still correct, please tell me how to measure the VHYS to meet 0.175Vsup(max).

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Mastermind 27690 points

    Kawasaki-san,

    VHYS is measured under recommended operating conditions, what issue did your customer meet when testing this parameter? Did their measured value higher than 0.175VSUP? If so please include a waveform so we can understand how it is deviated from datasheet spec.

    Regards,

    Sean

  • 0 in reply to Sean Guo
    Intellectual 851 points

    Hello Sean-san,

    I got plots from them as shown in the attached.  They don't see VHYS is in the spec.  Would you please tell me what they misunderstand here?

    TLIN2029A-Q1_VHYS.xlsx

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Mastermind 27690 points

    Hi Kawasaki-san,

    The VBUSrec and VBUSdom are the voltage threshold that the RXD output switch from dominant to recessive when the LIN bus voltage ramps up and  switch from recessive to dominant when the LIN bus voltage ramps down. And those parameters are voltage inputs which means the the LIN transceiver works as a receiver,  your customer should drive LIN bus with a voltage ramp checking the entire dominant and recessive signal area with respect to the applied VSUP, see the figure below. 

    Please send an email to me at s-guo2@ti.com so I can share the C&S Conformance test report which includes test results of VHYS.

    Regards,

    Sean

  • 0 in reply to Sean Guo
    Intellectual 851 points

    Hello Sean-san,

    Thank you very much for pointing out the frequency difference between the spec and their results.  I understand if they apply 20Hz to LIN input, they should be able to get the same results.  I'll send you email.

    Best Regards,

    Yoshikazu Kawasaki

  • 0 in reply to Yoshikazu Kawasaki
    TI__Mastermind 27690 points

    Hi Kawasaki-san,

    I have send you through e-mail. Let me know if you have more questions.

    Regards,

    Sean