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CCS/LDC1612: External inductive coils

Ali El-Zaghal
Intellectual 280 points
Part Number: LDC1612
Other Parts Discussed in Thread: LDCCOILEVM

Tool/software: Code Composer Studio

Hi,

I am working with LDC1612 using 1 external channel with an external coil, program my code to get inductance data from this channel, in my hardware i connected th coil directly on the channel terminals and while testing the voltage change using oscilloscope the volt change only with two values (max volt, min volt), there was no range of change despite when i use the boost internal coil i notice the change in voltage range.

I ask if i need to connect any hardware like capacitors or resistors with the coil before connecting it to the boost channel.

  • 0
    TI__Genius 17440 points

    Hello,

    Yes, the sensor is a parallel LC tank, not just a coil. Please reference the example application diagram in section 8.2.2 of the datasheet. If you have additional questions about configuring the device or inductive sensing in general, I recommend looking at the FAQ linked in my signature below. 

    Best Regards,

  • 0 in reply to Kristin Jones93
    Intellectual 280 points

    HI,

    Then how can i determine the value for C parameter  of the capacitor or depend on which of coil parameters i can choose it.

    best regards.

  • 0 in reply to Ali El-Zaghal
    TI__Genius 17440 points

    Hello,

    You should select your capacitor based on the Rp and f_sensor requirements for the LDC1612. The LDC1612 can only drive sensors with Rp values greater than 1kohm and f_sensor values between 1kHz and 10MHz. You can use the LDC Tools Excel Calculator (found either on the LDC1612 product page or in the E2E FAQ) to quickly calculate Rp and f_sensor based on your coil parameters.

    Best Regards,

  • 0 in reply to Kristin Jones93
    Intellectual 280 points

    hello Kristin, 

    How can i order an external coil for my application that can measure a gap up to 20 mm with high resolution of measuring and if i can find all coil parameters in it's own data sheet !

    best regard.

  • 0 in reply to Ali El-Zaghal
    TI__Genius 17440 points

    Hello,

    We have the LDCCOILEVM available for prototyping purposes. Coils H and I should work for you. However, these coils aren't available to use in production. You would need to design your own coil (or use an existing coil design from the LDCCOILEVM) and place it on the same PCB as your LDC1612 in production.

    Best Regards,

  • 0 in reply to Kristin Jones93
    Intellectual 280 points

    Hello Kristin,

    i checked the link you send to me, and i ask also if i need to design my own coil, i see tool from Ti before and can get all coil parameters i need for design, just asking about two points.

    1- if i want a gap equal to 20 mm could the layers number affect in minimizing the coil diameter, or only it used for high resolution measurement !

    2- when i use multi layers how can i separate them in the case of not using PCB, and ask if i using 1 mm plastic sheet between each planner coil and the other one, will work ! 

    best regards.

  • 0 in reply to Ali El-Zaghal
    TI__Genius 17440 points

    Hello,

    The number of layers and the spacing between layers will only affect the inductance of the coil, which does not affect the sensing distance nor resolution. If you reduce the outer diameter of the coil you will reduce the sensing distance and the resolution.

    We haven't supported this type of coil before so you will need to test this, but as long as the turns are not shorted together it should work.

    Best Regards,