SNOAA76 August   2021 LDC3114 , LDC3114-Q1

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Benefits of Inductive Proximity Sensing
    2. 1.2 Common Applications
    3. 1.3 Human-Machine Interface Design Guide
  3. 2System Considerations
    1. 2.1 Target Properties
    2. 2.2 Sensing Distance
    3. 2.3 LDC3114 Device Features
  4. 3Design
    1. 3.1 Sensor Size and Frequency
    2. 3.2 Linear Sensing Region
  5. 4Measured Raw Data Output
    1. 4.1 Measured Response of LDCCOILEVM Sensor N
    2. 4.2 Measured Response of LDCCOILEVM Sensor R
  6. 5Observed Effects of Ambient Temperature
  7. 6References

2.2 Sensing Distance

For inductive technology, 1 µm to 10 cm is a feasible sensing range. If an application requires high precision, a sensing range that is 50% of the coil diameter can be expected from most of the LDC devices. For example, a sensor with an outer diameter of 10 mm can be expected to have a sensing range of 5 mm. This range can be increased to 100% in low precision applications, such as a simple detection of metal presence.

It is important to note that sensitivity is greatest within 20% of the total sensing distance, and this should be considered when designing a system based on maximum required sensing distance.

Figure 2-2 illustrates the relative inductance shift versus distance and it can be seen that within 20% of the coil diameter, the shifts in inductance are stronger with respect to smaller distances. This allows for higher precision measurements, for example, an application with a sensor diameter of 10 mm could provide nanometer resolution within a target distance of 2 mm.

GUID-2CFD4327-056C-4C33-8E22-B8F09624A190-low.jpg Figure 2-2 Relative Inductance vs Distance of Various Coil Sizes