• State TI Thinks Resolved
  • Locked Locked
  • Replies 11 replies
  • Answers 3 answers
  • Subscribers 32 subscribers
  • Views 1556 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

HDC2010: Repeatability of +-0.1

user4198223
Prodigy 60 points
Part Number: HDC2010
Other Parts Discussed in Thread: TMP116

I was looking on HDC2010, can it be that this sensor has a +-0.2 Accuracy (page 5) while having Repeatability of +-0.1c? 

For ex the Repeatability of SI7021-A20 which has the same bit resolution and also is a humidity and temperature sensor is 0.01cRMS (page 9 in the SI7021-A20 data sheet)

is the +-0.1c is the same as 0.01cRMS? 

or

is the +-0.1c a tipo?

  • 0
    TI__Mastermind 35895 points
    Hi user,

    The competitor's device specifies °C RMS where we specify °C.

    Thanks,
    Ren
  • 0 in reply to Ren Schackmann
    Prodigy 60 points
    Thanks, Ran Schackmann, but this does not answer my question, I have also asked about what is the difference between c and cRMS regarding Repeatability. (better a full answer than a fast answer...)

    I was asking a bit around in our R&D department and they mean that in this discussion +-Xc and XcRMS are almost the same things.

    Is there some documentation on how the Repeatability is calculated?

    I am asking it as my company is delivering temperature monitoring solution with calibration and in order to calibrate this sensor we need to know what is TEMPREP in more details.

    Thanks.
  • 0 in reply to user4198223
    TI__Genius 11750 points
    Hi user,

    Thanks for your post. I'm in the process of acquiring this information and will list out the differences between the two once I get feedback.

    Best Regards,
    Matt
  • 0 in reply to Matthew Sauceda
    Prodigy 60 points

    Thanks you very much Matt, I am really interested in reading what you find.

    Thanks.

  • 0 in reply to user4198223
    TI__Genius 11750 points

    Hi user,

    The test setup involved to measure the parameter consists of keeping the device at a constant  temperature (oil bath), and observing the amount of code changes (steps) in the device.  For the value presented in the datasheet, it may be a more conservative representation, as it may be a magnitude less, and is generally typically influenced by noise, which often creates small code changes, typically1 LSB.

    Best Regards,

    Matt

  • 0 in reply to Matthew Sauceda
    Prodigy 60 points

    Hi Matthew,

    Thank you for the answer.

    Super, so the +-0.1 is the worst measurement difference, so you dont have a value like the RMS, which will then give the ~70% probability, which is probably better than 0.1...

    Thanks

  • 0 in reply to user4198223
    TI__Genius 11750 points
    Hi user,

    We don't typically specify RMS in our datasheets. Is there a reason why you would require this over the measurement parameters specified in our current datasheet?

    Best Regards,
    Matt
  • 0 in reply to Matthew Sauceda
    Prodigy 60 points

    Hi, sorry for the long time, was on vacation

    I have now found a better comparison:

    HDC2010 and TMP116:

    The TMP116 is really cool and have a really high accuracy. And it has a repeatability of +-1LSB (page 5) which translate to +-0.0078215c, it also explained really good how the repeatability is calculated, really nice! thumb up for decompensation!

    I know that TMP116 is much better in measuring temperature than the HDC2010, but when the HDC2010 repeatability is set to +-0.1, which is ~10 time bugger than its resolution, it is really interesting that the TMP116 has a repeatability = to resolution....

    I have now looked at many different humidity sensors, and almost all have the same repeatability of +-0.1. We need to deliver to our customers sensors with an accuracy of +-0.5 (that is easy). But we also need to make a calibration certificate that we do our self. With a repeatability so high, our setup needs to improve before we can deliver calibration certificates.

    Can there be something general with humid sensors, as there is some expose silicon for measuring humid that increases their repeatability so much in comparison to only temperature sensors?

    That might be a bit complex question, but it really put me off using humidity sensors.

  • 0 in reply to user4198223
    TI__Genius 11750 points
    Hi User,

    Thanks for the follow up, as mentioned the parameter value included in the datasheet may have additional margin, as it may be a magnitude less, and this value is only typically influence by noise, which often creates a small code change, ~1 LSB. This parameter may be updated as we start to produce future humidity sensing devices, however the current number is what we guarantee in our datasheets.

    Best Regards,
    Matt
  • 0 in reply to Matthew Sauceda
    Prodigy 60 points
    Hi Matt,

    Thanks for the good answer. I understand the ~1 LSB error and the adding of margin. But it still does not answer the core of the question, which I guess only a silicon/humidity sensor expert can. Why is there such a big difference on paper from humidity sensors repeatability to temperature sensor repeatability? My GUESS is that humidity sensor is more prone to noise...
  • 0 in reply to user4198223
    TI__Genius 11750 points
    Hi User,

    I don't believe this to be the case, as it probably is the environment in which humidity was measured at a given temperature. For instance, the equipment required to be the stimulus in humidity sensors is different from temperature sensors. As such, there may be more noise from the end equipment required for humidity measurements, as opposed to direct temperature measurements.

    Best Regards,
    Matt