• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 1618 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.

Metal Face Inductive Prox

Cameron MacKinnon
Prodigy 185 points
Other Parts Discussed in Thread: LMP91300, LDC1612, LDC0851, LDCCOILEVM, LDC1612EVM

We are looking at designing an inductive proximity sensor for harsh environment usage.

The unit will have a 316L Stainless Steel housing with a 0.3mm thick sensing face, which needs to be temperature compensated 0-100C

We'd like to detect a mild steel FE 37 target(12mmx12mmx1mm thick) at 2mm and turn off at 2.4mm, as the housing has already been designed we are limited to a 5.9mm max dia on the sensing coil.

We have proto-typed with the LMP91300, while it will function at ambient temperature range issues appear as the temperature climbs during testing.

-On and Off points creep from the set range of 2mm and 2.4mm   and we end up with a range of 1.6mm to 3mm

Is there a recommendation for a different chip which could perform better in this application?

  • 0
    TI__Genius 13650 points

    Hello Cameron,

    have you followed the guidelines for the look-up table calibration? Did you use the recommended NTC? If not, you may need to re-calibrate. 

    Yes, we do also have different LDCs available, such as the LDC1612 which uses a different measurement technique (frequency change rather than RP-proximity data). Frequency change is inherently less affected by temperature changes and does not require temperature compensation in many applications. 

  • 0 in reply to Ben Kasemsadeh
    TI__Genius 16890 points
    Hi Cameron,

    Please see the information in your other post:

    e2e.ti.com/.../1862734

    Thanks,

    Mike
  • 0 in reply to Michael Stout
    Prodigy 185 points

    Hi Ben,

    Does the LDC0851 work on the same principle as the LMP93100 or the LDC1612? One of my collegues wants to use it but if it uses Rp rather than frequency I'm concerned we will end up with something that functions but we will be unable to produce easily in quanity.

    Cam


  • 0 in reply to Cameron MacKinnon
    TI__Genius 13650 points
    Hi Cameron,
    The LDC0851 is similar to the LDC1612 in that it measures L (not RP).

    It operates a bit differently from the LDC1612: the LDC1612 takes a frequency measurement and reports the code output. On the other hand, the LDC0851 takes two frequency measurements (one on the sense coil and one on the reference coil), and compares them. By using this approach, the LDC0851 greatly reduces any temperature effects, because any variation in ambient temperature is seen by both the sense and the reference coil simultaneously.
  • 0 in reply to Ben Kasemsadeh
    Prodigy 185 points
    Hi Ben,

    We tried using the LDC0851 and could not get the range we required for our application to be successful. With the coil diameter we are limited to we are unable to get more than 1.8mm range. We are now preparing to evaluation the LDC1612 (we are planning on ordering the LDCCOILEVM as well as the LDC1612EVM). Does TI have a recommended MCU to pair with the LDC1612? Secondly are there any MCU's that have I/O which can function as an AFE? We don't need to determine the type of metal we just need to reliably detect it at a nominal range of 4mm.
  • 0 in reply to Cameron MacKinnon
    TI__Genius 13335 points
    Hello Cameron,
    The LDC1612EVM comes with an MSP430 for the MCU. The specific part number is: MSP430F5528IRGC
    Regards,
    Luke