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LDC1000 device ID

Vasco Tesi46
Intellectual 360 points
Other Parts Discussed in Thread: LDC1612, LDC1614, LDC1312, LDC1314, LDC1101

Hi, using an LDC1000 (sure of that, because the marking is LDC1000 with no suffix), is it possible that reading device ID (address 0x00) we get 0x80 and not 0x84 as per LDC1000 datasheet ? 

bye, Vasco (relevant timing diagram attached)

  • 0
    TI__Genius 13650 points
    Hi Vasco,
    I will look into your request and get back to you tomorrow.
  • 0 in reply to Ben Kasemsadeh
    TI__Genius 13650 points
    Hi Vasco,
    you are right, the documentation is incorrect. I made a request to update the datasheet.

    Have you considered using one of our newer devices for this application? They offer many advantages over the LDC1000:
    - The high-resolution multi-channel LDCs (LDC1612, LDC1614) are L-only devices which offer greatly improved measurement accuracy, better part-to-part variation, lower power consumption, easier design integration, and multiple channels.
    - The mid-resolution multi-channel LDCs (LDC1312, LDC1314) are L-only devices which offer better part-to-part variation, lower power consumption, easier design integration, and multiple channels.
    - The high-resolution, high-speed LDC1101 supports both L- and RP-measurements, greatly improved measurement accuracy, better part-to-part variation, lower power consumption, and easier design integration.
  • 0 in reply to Ben Kasemsadeh
    Intellectual 360 points
    Hi Ben, thanks.
    I did not take into account LDC1101; i need both L and Rp measurements so the others are not interesting for me (not for the application to whom i'm working now).

    Now i will study LDC1101 datasheet.

    LDC1000 also has 16 bit Rp and 24 bit L measurements; if you have some time for me, please explain why LDC1101 should be better in terms of accuracy and repeatability as compared to LDC1000.
    Sure it's advantageous for being operating at lower voltages.
    Bye, Vasco
  • 0 in reply to Vasco Tesi46
    Intellectual 360 points
    anyway, please tell me about foreseen cycle life of LDC1000 , now that there's its improved version. Please note that LDC1101 is not a substitute of LDC1000, it has different ratings of Rp and resonant frequency. In my design probably i would be obliged to make the sensor operate at an higher frequency in order to match LDC1101 Rp and Q requirements.
  • 0 in reply to Vasco Tesi46
    TI__Genius 13650 points
    Hi Vasco,
    the LDC1000 is active and in production. Usually customers prefer the newer LDC1101 because its many advantages. You are right; the minimum oscillation frequency of the LDC1000 is lower, which is why it is the recommended device for metal type identification applications which rely on a low oscillation frequency.
  • 0 in reply to Ben Kasemsadeh
    TI__Genius 13650 points
    Hi Vasco,
    also, the LDC1101 has the LHR mode which results in significantly better SNR. Additionally, it has 10x smaller part-to-part variation than the LDC1000.
  • 0 in reply to Ben Kasemsadeh
    Intellectual 360 points

    Hi Ben, 

    now I  repeat one question and I will try to be more precise. 

    In LDC1101 Rp measurement variation from part to part is reported in a single configuration sample. 

    Can you provide some formulas or some criterion which allows me, and everyone who read this forum, to estimate part to part Rp measurement variation, including LDC1000 ? 

    Thanks, Vasco 

  • 0 in reply to Vasco Tesi46
    TI__Genius 13650 points

    Hi Vasco,

    the LDC1101 part-to-part variation is in the datasheet (refer to Isensormax in the electrical characteristics). 

    There is no equivalent spec on the LDC1000, but the delta between typ and the limits would  be approximately 10x higher on the LDC1000 compared to the LDC1101.

  • 0 in reply to Ben Kasemsadeh
    Intellectual 360 points

    Hi Ben, thank you for your hints. 

    My application involves estimation of metal surface conductivity; I'd prefer to continue using LDC1000, because its Rp and Q requirements match my needs better than LDC1101. 

    So, is it possible to correct LDC1000 part to part Rp measurement variation, using some sort of calibration? For example, by measurement of a specimen of known characteristic with fixed geometric relationship between specimen and sensor? 

    thanks again, bye. Vasco 

  • 0 in reply to Vasco Tesi46
    TI__Genius 13650 points
    Hi Vasco,
    yes, you can have a one-time calibration in which the system measures a known target in either one or two known positions. The MCU could then store this data in non-volatile memory and use the information whenever the system is powered on. This approach can be used to compensate for part-to-part variation in precision applications.