SNOSCZ5B June   2015  – October 2024 FDC2112 , FDC2114 , FDC2212 , FDC2214

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics - I2C
    8. 6.8 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Clocking Architecture
      2. 7.3.2 Multi-Channel and Single-Channel Operation
      3. 7.3.3 Gain and Offset (FDC2112, FDC2114 Only)
      4. 7.3.4 Current Drive Control Registers
      5. 7.3.5 Device Status Registers
      6. 7.3.6 Input Deglitch Filter
    4. 7.4 Device Functional Modes
      1. 7.4.1 Start-Up Mode
      2. 7.4.2 Normal (Conversion) Mode
      3. 7.4.3 Sleep Mode
      4. 7.4.4 Shutdown Mode
        1. 7.4.4.1 Reset
    5. 7.5 Programming
      1. 7.5.1 I2C Interface Specifications
    6. 7.6 Register Maps
      1. 7.6.1  Register List
      2. 7.6.2  Address 0x00, DATA_CH0
      3. 7.6.3  Address 0x01, DATA_LSB_CH0 (FDC2212 / FDC2214 only)
      4. 7.6.4  Address 0x02, DATA_CH1
      5. 7.6.5  Address 0x03, DATA_LSB_CH1 (FDC2212 / FDC2214 only)
      6. 7.6.6  Address 0x04, DATA_CH2 (FDC2114, FDC2214 only)
      7. 7.6.7  Address 0x05, DATA_LSB_CH2 (FDC2214 only)
      8. 7.6.8  Address 0x06, DATA_CH3 (FDC2114, FDC2214 only)
      9. 7.6.9  Address 0x07, DATA_LSB_CH3 (FDC2214 only)
      10. 7.6.10 Address 0x08, RCOUNT_CH0
      11. 7.6.11 Address 0x09, RCOUNT_CH1
      12. 7.6.12 Address 0x0A, RCOUNT_CH2 (FDC2114, FDC2214 only)
      13. 7.6.13 Address 0x0B, RCOUNT_CH3 (FDC2114, FDC2214 only)
      14. 7.6.14 Address 0x0C, OFFSET_CH0 (FDC21112 / FDC2114 only)
      15. 7.6.15 Address 0x0D, OFFSET_CH1 (FDC21112 / FDC2114 only)
      16. 7.6.16 Address 0x0E, OFFSET_CH2 (FDC2114 only)
      17. 7.6.17 Address 0x0F, OFFSET_CH3 (FDC2114 only)
      18. 7.6.18 Address 0x10, SETTLECOUNT_CH0
      19. 7.6.19 Address 0x11, SETTLECOUNT_CH1
      20. 7.6.20 Address 0x12, SETTLECOUNT_CH2 (FDC2114, FDC2214 only)
      21. 7.6.21 Address 0x13, SETTLECOUNT_CH3 (FDC2114, FDC2214 only)
      22. 7.6.22 Address 0x14, CLOCK_DIVIDERS_CH0
      23. 7.6.23 Address 0x15, CLOCK_DIVIDERS_CH1
      24. 7.6.24 Address 0x16, CLOCK_DIVIDERS_CH2 (FDC2114, FDC2214 only)
      25. 7.6.25 Address 0x17, CLOCK_DIVIDERS_CH3 (FDC2114, FDC2214 only)
      26. 7.6.26 Address 0x18, STATUS
      27. 7.6.27 Address 0x19, ERROR_CONFIG
      28. 7.6.28 Address 0x1A, CONFIG
      29. 7.6.29 Address 0x1B, MUX_CONFIG
      30. 7.6.30 Address 0x1C, RESET_DEV
      31. 7.6.31 Address 0x1E, DRIVE_CURRENT_CH0
      32. 7.6.32 Address 0x1F, DRIVE_CURRENT_CH1
      33. 7.6.33 Address 0x20, DRIVE_CURRENT_CH2 (FDC2114 / FDC2214 only)
      34. 7.6.34 Address 0x21, DRIVE_CURRENT_CH3 (FDC2114 / FDC2214 only)
      35. 7.6.35 Address 0x7E, MANUFACTURER_ID
      36. 7.6.36 Address 0x7F, DEVICE_ID
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Sensor Configuration
      2. 8.1.2 Shield
      3. 8.1.3 Power-Cycled Applications
      4. 8.1.4 Inductor Self-Resonant Frequency
      5. 8.1.5 Application Curves
    2. 8.2 Typical Application
      1. 8.2.1 Schematic
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Recommended Initial Register Configuration Values
      4. 8.2.4 Application Curve
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.1.3 Power-Cycled Applications

For applications which do not require high sample rates or maximum conversion resolution, the total active conversion time of the FDC can be minimized to reduce power consumption. This can be done by either by using sleep mode or shutdown mode during times in which conversions are not required (see Device Functional Modes).

As an example, for an application which only needs 10 samples per second with a resolution of 16 bits can utilize the low-power modes. The sensor requires SETTLECOUNT = 16 and IDRIVE of 01111b (0.146mA). Given FREF = 40MHz and RCOUNT = 4096 will provide the resolution required. This corresponds to 4096 * 16 * 10 / 40MHz → 16.4ms of active conversion time per second. Start-up time and channel switch delay account for an additional 0.34ms. For the remainder of the time, the device can be in sleep mode: Therefore, the average current is 19.4ms * 3.6mA active current + 980.6ms of 35µA of sleep current, which is approximately 104.6µA of average supply current. Sleep mode retains register settings and therefore requires less I2C writes to wake up the FDC than shutdown mode.

Greater current savings can be realized by use of shutdown mode during inactive periods. In shutdown mode, device configuration is not retained, and so the device must be configured for each sample. For this example, configuring each sample takes approximately 1.2ms (13 registers * 92.5 µs per register). The total active time is 20.6ms. The average current is 20ms * 3.6mA active current + 980ms * 2µA of shutdown current, which is approximately 75µA of average supply current.