SNOA930C March   2015  – May 2021 LDC0851 , LDC1001 , LDC1001-Q1 , LDC1041 , LDC1051 , LDC1101 , LDC1312 , LDC1312-Q1 , LDC1314 , LDC1314-Q1 , LDC1612 , LDC1612-Q1 , LDC1614 , LDC1614-Q1 , LDC2112 , LDC2114 , LDC3114 , LDC3114-Q1

 

  1.   Trademarks
  2. 1The Sensor
    1. 1.1 Sensor Frequency
    2. 1.2 RS and RP
      1. 1.2.1 AC Resistance
      2. 1.2.2 Skin Effect
  3. 2Inductor Characteristics
    1. 2.1 Inductor Shape
      1. 2.1.1 Example Uses of Different Inductor Shapes
    2. 2.2 Number of Turns
    3. 2.3 Multiple Layers
      1. 2.3.1 Mutual Inductance of Coils in Series
      2. 2.3.2 Multi-Layer Parallel Inductor
      3. 2.3.3 Temperature Compensation
    4. 2.4 Inductor Size
    5. 2.5 Self-Resonance Frequency
      1. 2.5.1 Measurement of SRF
      2. 2.5.2 Techniques to Improve SRF for Wire-wound Inductors
  4. 3Capacitor Characteristics
    1. 3.1 Capacitor RS, Q, and SRF
    2. 3.2 Effect of Parasitic Capacitance
      1. 3.2.1 Recommended Capacitor Values
    3. 3.3 Capacitor Placement
  5. 4Physical Coil Design
    1. 4.1 Example Design Procedure Using WEBENCH
      1. 4.1.1 General Design Sequence
    2. 4.2 PCB Layout Recommendations
      1. 4.2.1 Minimize Conductors Near Sensor
      2. 4.2.2 Sensor Vias and Other Techniques for PCBs
  6. 5Summary
  7. 6References
  8. 7Revision History

4.1.1 General Design Sequence

The recommended sensor design process is:

  1. Determine the maximum size inductor that can physically be used in the application, and set the dOUT value to that size. If the sensor is near the edge of a PCB, be sure to include any edge clearance rules from the PCB manufacturing rules.
  2. Based on the PCB manufacturing rules, set:
    1. Trace Width and Trace Space to the minimum permitted. This value is commonly between 4 mils (0.1 mm) and 6 mils (0.15 mm).
    2. Copper thickness; this is commonly 1 oz-cu (approximately 35 µm). Thicker is better.
  3. Set the Number of Layers to match the number of board layers in the design.
  4. Set the Capacitance — the range of 300 pF to 2 nF is typically near the optimum unless a specific sensor frequency is needed. Adjust the capacitance as needed if the sensor frequency is not with the device limits.
  5. Set the number of turns so that the ratio of Din / Dout is > 0.3.
  6. Export the design into the desired format.