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LDC Detection of small metal

na na78
Guru 16770 points
Other Parts Discussed in Thread: LDC1612

Hi

We want to detect a small size chip coil by LDCs.
Assumed chip size is 0402.

Is it possible to detect small chip coils?
What do you think what kind of LDC device is suitable for such applications?

ragards

  • 0
    TI__Genius 13650 points

    Hello Na na,

    do you mean using an 0402 inductor as a sensor?

    Sensing range will be very limited. It may be possible to use such a small inductor for extremely close proximity sensing applications.

    Keep in mind that 

    1. Different SMD inductor styles provide different results in terms of sensing range and sensing direction, depending on how the coil inside is wound.

    2. Inductors of this physical size probably won't have enough inductance to be driven by the LDC in default configuration. Use The LDC1612 in HIGH_CURRENT_DRV = b1 mode (single-channel only) to reduce the minimum inductance that you can drive. Additionally, it may be necessary to add a fixed series inductor that is not used as a sensor (

    Inductive sensing: How to use a tiny 2mm PCB inductor as a sensor
    Recently, a customer asked me if he could use a tiny PCB coil as the sensing element for the LDC1000 inductance-to-digital converter (LDC). The PCB coil had only three turns per PCB layer on a four-layer…
    By in Technical articles > Analog
     )

  • 0 in reply to Ben Kasemsadeh
    Guru 16770 points

    Hi Ben

    Thank you for your information and I apologize my explanation was not enough.

    We are going to detect the existence or non-existence of discrete semiconductors inside embossed taping, using inductive sensing. (Targets are metals because they has own pins.)

    So, if the target is a chip inductor, its size is 0402.

    We will select LDC1612/14.
    Next, we have to select what kind of inductor as sensor is good for this application.


    regards

  • 0 in reply to na na78
    TI__Genius 13650 points
    Hello Na na,
    Yes, you can sense very small targets, but keep in mind that a larger target affects the inductance change much more than a small one. Refer to this blog for details: e2e.ti.com/.../inductive-sensing-target-size-matters .
    The best system in this case would have a relatively small coil with many layers that is very close to the target. This apps note provides more information on sensor design: www.ti.com/.../snoa930.pdf