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SN65LDVS9637 input fail safe threshold

Is there any data on the input fail safe threshold, eg minimum, maximum, hysteresis, response time etc.

The datasheet merely says about 2.3V but sometimes says 2.4V and other times it says 2.35V

Thanks


Alex

  • Hi Alex,

    you are right, the datasheet only states the receiver open-circuit threshold voltage to be about 2.3V.

    The 2.35V describe the max. common-mode input voltage and the 2.4V are given as the minimum supply voltage for the drivers / receivers.

    Due to the fact that this device was released back in 1997 I am sorry to say we don't have any data exceeding what is given in the datasheet.

    The only thing I could offer would be to take some measurements at the bench without beeing able to give you guaranteed min / max values for the threshold voltage.

    Please let me know if you have further questions or how I can assist you.

    Best regards,

    Chris

  • Hi Chris,

    It didn't take you long to find that there is nothing. Is it that everything pre 1997 is not on the computer system yet?
    If there really is no further data, perhaps someone can provide an opinion based on the IC circuit?

    Regards
    Alex
  • Alex,
    it is not that no data is available for any devices released 1997 or earlier in general. It only decreases the propability.
    I will talk to our designers about your request and try to get further information and come back to you as soon as I can.
    Best regards,Chris
  • Hi Chris,

    Thanks for going forward with this,

    Best regards,

    Alex

  • Hi  Chris,

    I've done some measurements and have found that the threshold is about 2.6-2.7V.

    I used some copper clad board and 10k preset pots (filtered with 100nF) to set the input levels.

    If I hold the Inverting input at 3.3V and move the non-inverting input then the output switches high when the non-inverting input goes above 2.7V and then the output switches low when the non-inverting input falls below 2.6V

    However, if I hold the non-inverting input above the threshold (eg at 3.3V) and move the inverting input then the output remains high except when the non-inverting input is at about 2.65V. At that point the output has random 10ns negative going pulses. Below and above that voltage the output remains steadily high.

    Best regards


    Alex

  • Hi Alex,

    thanks for sharing your results.

    The value for the threshold has never been characterized, so I can't provide any valid data on this.

    Please be aware that your measurements exceed the recommended differential input voltage range (0.1V to 0.6V) as well as the range for the input common-mode voltage (0.05V to 2.35V for VID = 0.1V, else even smaller).

    If you hold one of the inputs at 3.3V you can not satisfy both criteria at once anymore.

    I will try to get one of those parts next week and do some measurements in our lab as well.

    Best regards,

    Chris