LDC1312: how can i increase the amount of change of LD1312

Part Number: LDC1312

Hi,

how can I increase the amount of change of LD1312.

only 20 units change when the metal touches to the antenna.

The following picture is an excerpt from the LDC Selection guide.( http://www.ti.com/lit/an/snoa954b/snoa954b.pdf )

why is the red box N/A ?

3 Replies

  • Hi Orhan,

    You could be experiencing a very small output code change because the target size is very small compared to the sensor size or the target is not a good conductor. LDC devices see the strongest response when the target size is about the same size as the sensor inductor. It's also important that the target is a good conductor, like copper or aluminum. Some stainless steels will also work. For more information about LDC target design and LDC sensor design, please refer to the linked app notes. 

    The red box is marked N/A because the LDC131x and LDC161x do not perform Rp measurements, only L measurements. This means that these devices are only monitoring the change in sensor inductance, not the change in Rp, which is a representation of the resistive losses due to the target's interaction with the sensor.

    Regards,

    Kristin Jones

    Sensor Signal Conditioning

    Applications Engineering

  • In reply to Kristin Jones93:

    Hi Kristin, thanks for your answer,

    We are using LDC1000 but we want to change another LDC devices.(very expensive compared to other LDC and other reasons. )

    LDC1000 output change is about 1000 unit, but LDC1612 output change very small.(20-50 unit) as I wrote above. (Same target metal)

    You said, you could use metal detection  to  LDC1312 on datasheet (www.ti.com/.../ldc1312.pdf)

    Only If I can measure L, how can I use as a metal detector? Output change is very small of LDC1312 according to LDC1000.

  • In reply to orhan ocak74:

    Hi Orhan,

    I am not sure why you are seeing such a small output code response from the LDC1612. The LDC1612 is higher resolution than the LDC1000, so it should have a better response. It is likely based on your system setup. If your sensor and target are designed within the guidelines of the app notes I shared, I would suggest checking that your sensor oscillation amplitude is between 1.2-1.8V. If not, you will need to modify your inductor or your capacitor.

    We differentiate between metal detection and metal identification. The LDC1612 can perform metal detection because this only requires that the sensor reacts in the presence of a metal target. This does not require Rp measurement, unlike metal identification.

    Regards,

    Kristin Jones

    Sensor Signal Conditioning

    Applications Engineering