SLYA048B March   2020  – June 2021 FDC1004 , FDC1004-Q1 , FDC2112 , FDC2112-Q1 , FDC2114 , FDC2114-Q1 , FDC2212 , FDC2212-Q1 , FDC2214 , FDC2214-Q1 , LDC0851 , LDC1001 , LDC1041 , LDC1051 , LDC1101 , LDC1312 , LDC1312-Q1 , LDC1314 , LDC1314-Q1 , LDC1612 , LDC1612-Q1 , LDC1614 , LDC1614-Q1 , LDC2112 , LDC2114 , LDC3114 , LDC3114-Q1

 

  1.   Trademarks
  2. 1Inductive and Capacitive Theory of Operation
    1. 1.1 Inductive Sensing Theory of Operation
    2. 1.2 Capacitive Sensing Theory of Operation
  3. 2FDC: Capacitive Level Sensing
    1. 2.1 Capacitive Technology Benefits in Liquid Level Sensing
    2. 2.2 Getting Started With Capacitive Liquid Level Sensing
    3. 2.3 Device Selection
    4. 2.4 Design Challenges and Additional Collateral
  4. 3LDC: Inductive Touch Buttons
    1. 3.1 Inductive Technology Benefits in Buttons
    2. 3.2 Getting Started With Inductive Buttons
    3. 3.3 Device Selection
    4. 3.4 Design Challenges and Additional Collateral
  5. 4LDC: Incremental Encoder and Event Counting
    1. 4.1 Inductive Technology Benefits in Incremental Encoders
    2. 4.2 Getting Started With an Inductive Incremental Encoder
    3. 4.3 Device Recommendations
    4. 4.4 Design Challenges and Additional Collateral
  6. 5LDC: Metal Proximity Sensor
    1. 5.1 Inductive Technology Benefits in Metal Proximity Detection
    2. 5.2 Criteria to Consider when Choosing Inductive Sensing for Metal Proximity Applications
      1. 5.2.1 Metal Target Movement in Relation to Inductive Coil
      2. 5.2.2 Sensing Distance
      3. 5.2.3 Size and Shape of Metal Target
      4. 5.2.4 Speed (Sample Rate versus Resolution)
      5. 5.2.5 Environmental Compensation
    3. 5.3 Getting Started With Inductive Metal Proximity Sensing
    4. 5.4 Device Recommendations
    5. 5.5 Design Challenges and Additional Collateral
  7. 6Revision History

1.2 Capacitive Sensing Theory of Operation

TI's FDC1004 uses a traditional switched-cap approach to capacitive sensing. It includes an active shield driver that helps concentrate fields to a desired direction. This is useful in liquid sensing applications if the engineer only wants to monitor the direction of the liquid instead of the added effects of human hands or other parasitic capacitances in the area.

The sensor electrode for a liquid level sensing system consists of both a sense and ground electrode. The device measures the fringe capacitance between the two electrodes, which can vary as the dielectric (or level of liquid) varies.

GUID-EEA14A91-B390-477C-8DA0-92915D372CB4-low.pngFigure 1-3 Capacitive Sensing Applications