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LM63: LM63CIMA tHD:DAT meansure fail

Richard Guo
Prodigy 10 points
Part Number: LM63

Hi Ti,

I measure tHD:DAT waveform and data hold time fail,spec is 300~930ns,test result is about 60ns,so fail.

 

I also refer SMbus web newest verion 3.1 spec. tHD:DAT hold time is min.0 ns. Can I refer to this file for measure waveform?

http://smbus.org/specs/SMBus_3_1_20180319.pdf 

Thanks

Richard Guo

  • 0
    TI__Mastermind 43715 points

    Hi Richard,

    LM63 has it's own unique specification which is not overridden by any third-party specification.

    thanks,

    ren

  • 0 in reply to Ren Schackmann
    Prodigy 10 points

    Hi Ren,

    SMBus should be a general specification, right? I refer to the SMBus specification, and tHD hold time is also  minimum of 0ns.

    So can't LM63 be used on the latest platform in the future?

    Thanks,

    Richard Guo

  • 0 in reply to Richard Guo
    TI__Guru* 91206 points

    Richard, if you read the SMBus specification and the note (Note 2 on page 18) associated with it, along with the logic that SMBus provides as to why they made the change to match I2C specification (page 83) - you will see this is should not be an issue - please do let us know if you actually see a problem, when  you using the device. 

    Also, when you remeasure this, you may want to check the spec and adjust your scope markers to the points that both I2C and SMBus indicate are the time periods for measuring the hold time, for both the time after a repeated start and hold time in general.

  • 0 in reply to Josh Wyatt
    Prodigy 10 points

    Hi Josh,

    Thank you for helping me confirm that there is no issue. There is no problem in actual use, only the measured signal doesn't meet the tHD hold time in LM63's spec.

    I remeasure this signal and the result is the same. 

    Thanks,

    Richard Guo

  • 0 in reply to Richard Guo
    TI__Guru* 91206 points

    Richard - 

    If you would be so kind as to stretch out your measurement so you can actually see the 30% (of SCL falling) to 30% (of SDA falling) that may help us understand your screen capture fully.