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LMP91300 max sensing distance I can get?

Henrik Waldemar
Prodigy 150 points
Other Parts Discussed in Thread: LMP91300, CC3200, LDC1612

Hello E2E Community

I have to design and make a Inductive Proximity Sensor for an unit to detect objects in pipes. The thing is that the metal on the objects is up to 15mm away from the position of the sensor. Is it possible to get a 15mm sensing distance from the LMP91300 and its circuit?

Best regards

Henrik Waldemar

  • 0
    TI__Genius 9300 points
    Hi Henrik,

    What material are the pipes, and how big are the obects? To make sure, the objects are metal, correct?
  • 0 in reply to Evgeny Fomin
    Prodigy 150 points
    Hi Evgeny

    It is pipes in a pneumatic post system I want to detect. A postal tube can be seen on the picture in the link: dl.dropboxusercontent.com/.../2015-02-23%2008.35.30.jpg

    There is 11 rings made of steel and underneath those there is a perforated sheet of steel.

    The postal tubes is send around in a huge system of pipes, from place to place. Those transport pipes is made of both plastic and steel and is 100mm i diameter. Take a look: dl.dropboxusercontent.com/.../2015-02-20%2011.21.55.jpg

    My task is to detect the pipes when they rush through the transport pipe with 10m/s. The distance from the sensor and the 11 rings on the postal tubes can vary from 7 - 14mm.

    So I need to know whether it is possible to detect the postal tubes in that system

    Best Regards

    Henrik W
  • 0 in reply to Henrik Waldemar
    TI__Genius 9300 points
    Hi Henrik,

    Thanks for your explanation of the system.

    Is there a chance you could have a small MCU? It would make the application implementation significantly simpler with a product from our LDC family.
    Basically, with LMP91300 you would have to calibrate each sensor during production for switch distance of 14mm.
    If using an LDC device + MCU you will not need production calibration step, MCU will rather be looking at sudden change in the output data of LDC device and report an event once it occurs.
  • 0 in reply to Evgeny Fomin
    Prodigy 150 points
    Hi Evgeny

    Thanks for your answers so far!

    The idea is that the collected data from the LMP91300 should be send via wifi to a local server. So a MCU is inevitable i think :) I have purchased the CC3200 launch pad to test the setup. If it work well I have to make the PCB myself.

    Is there a chip in the LDC family you would recommend to me? Can the LDC give me an interrupt when the value has changed ? And what is the sensing distance of this application?

    Best Regards Henrik W
  • 0 in reply to Evgeny Fomin
    Prodigy 150 points
    I have read a little about the LDC1000 now. And found out that the Maximum sensing distance is 8mm with a 14mm PCB coil. Can this Maximum sensing distance be extended to 14mm with another coil design or is the LDC1000 not the right chip for me in the LDC family?

    Best Regards Henrik W
  • 0 in reply to Henrik Waldemar
    TI__Genius 9300 points
    Hello Henrik,

    LDC1000 is a good candidate for this app. Our highest resolution device is LDC1612, you may choose to test both to evaluate their performance.
    LDC1000 has a trigger, same as LMP91300, but unlike 91300, it does not have a temp. compensation.
    1612 does not have a trigger, it will have to be SW-implemented, which is very easy, really.
    14mm is quite achievable with larger coil diameter. Ideal solution would be to wrap the coil around those pipes - then it will have plenty of sensitivity. For coil design please take a look at Webench tool.