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ADS1018 shared signal to SN74LVC2T45DCTR

user4640884
Prodigy 30 points

Hi, I have a question about if its good to connect together the same signal from AIN1 / AIN2 / AIN3 to A1 / A2 from a level converter SN74LVC2T45DCTR.

This is beacause in my device its posible to have both analog and digital signal. So I have to connect the same pins together ( AIN1 to A1 and AIN2 to A2 ).

Can I do this directly or I have to put some protections.

Thanks!

  • 0
    TI__Intellectual 1610 points

    Hello user4640884,

    Thank you for your inquiry. Can you please elaborate on what you are trying to do here?

    Do you mean a connection from 1) A1 to both, AIN1 and AIN3, and 2) A2 to both, AIN2 and AIN4

    OR

    Do you mean you are measuring SIGNAL X going to A1 of the level converter SN74LVC2T45DCTR and the same SIGNAL X goes to AIN1 of the ADC. In other words, are you measuring the analog part of the signal with the ADC and the digital part goes through the SN74LVC2T45DCTR?



    Thanks,
    Krunal

  • 0 in reply to Krunal Maniar
    Prodigy 30 points

    Hello Krunal, thank you for the quick reply.

    I mean your second explanation. I measuring a Signal X that I don't know what type is. It could be analog or digital. So I have to put this Signal X to A1 of SN74LVC2T45DCTR and the same time, Signal X goes to AIN1 of the ADC.

    Analog signal could be from 300-1250mv

    Digital signal could be TTL, SDI-12, or 3.6v level

    I send a photo to see it clear:

    Thanks,

  • 0 in reply to user4640884
    TI__Intellectual 1610 points

    Hello user4640884,


    Thank you for the follow up. I just have few comments:

    Just a word of caution, I see that the input voltage to the ADC can go as high as 3.6 V whereas the analog supply to ADC is 3.3 V. This is right on the edge of the absolute maximum rating specification for the input voltage range. I would recommend to keep VIN <= VCC at all times. This could also be useful to prevent any excessive current through the ADC's internal ESD protection diodes. 

    I would also recommend using an anti-aliasing filter (a single-order RC) at the input of the ADC to attenuate high-frequency noise to the ADC.

    Thanks,

    Krunal

  • 0 in reply to Krunal Maniar
    Prodigy 30 points

    Hellor Krunal, I take into account the voltage. This is why I put 5v as alternative voltage.

    But, what I mean is if I can put this Signal X to A1 of SN74LVC2T45DCTR and the same Signal X goes to AIN1 of the ADC.

    Is a good connection, or there is a better solution?

    Thank you very much

  • 0 in reply to user4640884
    TI__Intellectual 1610 points
    Hello user4640884,

    You should be good with this solution.

    Regards,
    Krunal