JAJSJX3 December   2021 LDC3114

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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 Digital Interface
    7. 6.7 I2C Interface
    8. 6.8 Timing Diagram
    9. 6.9 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Multimode Operation
      2. 7.3.2 Multichannel and Single-Channel Operation
      3. 7.3.3 Raw Data Output
      4. 7.3.4 Button Output Interfaces
      5. 7.3.5 Programmable Button Sensitivity
      6. 7.3.6 Baseline Tracking
      7. 7.3.7 Integrated Button Algorithms
      8. 7.3.8 I2C Interface
        1. 7.3.8.1 I2C Interface Specifications
        2. 7.3.8.2 I2C Bus Control
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Power Mode
      2. 7.4.2 Low Power Mode
      3. 7.4.3 Configuration Mode
    5. 7.5 Register Maps
      1. 7.5.1 LDC3114 Registers
      2. 7.5.2 Gain Table for Registers GAIN0, GAIN1, GAIN2, and GAIN3
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Theory of Operation
      2. 8.1.2  Designing Sensor Parameters
      3. 8.1.3  Setting COM Pin Capacitor
      4. 8.1.4  Defining Power-On Timing
      5. 8.1.5  Configuring Button or Raw Data Scan Rate
      6. 8.1.6  Programming Button or Raw Data Sampling Window
      7. 8.1.7  Scaling Frequency Counter Output
      8. 8.1.8  Setting Button Triggering Threshold
      9. 8.1.9  Tracking Baseline
      10. 8.1.10 Mitigating False Button Detections
        1. 8.1.10.1 Eliminating Common-Mode Change (Anti-Common)
        2. 8.1.10.2 Resolving Simultaneous Button Presses (Max-Win)
        3. 8.1.10.3 Overcoming Case Twisting (Anti-Twist)
        4. 8.1.10.4 Mitigating Metal Deformation (Anti-Deform)
      11. 8.1.11 Reporting Interrupts for Button Presses, Raw Data Ready and Error Conditions
      12. 8.1.12 Estimating Supply Current
    2. 8.2 Typical Application
      1. 8.2.1 Touch Button Design
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 サポート・リソース
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

8.2.1.2 Detailed Design Procedure

The LDC3114 is a multichannel device. The italic n in the parameters below refers to the channel index:

  1. Select system-based options:
    • Select Normal or Low Power Mode of operation by setting the LPWRB pin to VDD or ground, respectively. Configure the enable bits for all channels in Register EN (Address 0x0C).
    • Select the polarities of OUTn and INTB pins by configuring Register OPOL_DPOL (Address 0x1C) and Register INTPOL (Address 0x11).
    • Configure the sensor frequency setting in Registers SENSORn_CONFIG (Addresses 0x20, 0x22, 0x24, 0x26).
  2. Choose the sampling rate (80, 40, 20, 10, 5, 2.5, 1.25, or 0.625 SPS) based on system power consumption requirement, and configure Register NP_SCAN_RATE (Address 0x0D) or Register LP_SCAN_RATE (Address 0x0F).
  3. Choose the button sampling window based on power consumption and noise requirements (recommended: 1 ms to 8 ms). While a longer button sampling window provides better noise performance, 1 ms is typically sufficient for most applications. Set SENCYCn and LCDIV in Registers SENSORn_CONFIG (Addresses 0x20, 0x22, 0x24, 0x26) and Register LC_DIVIDER (Address 0x17) in the following steps:
    • Calculate LCDIV = ceiling (log2 (fSENSORn × tSAMPLEn) – 12), where fSENSORn is the sensor frequency in MHz, tSAMPLEn is the button sampling window in µs.
    • If LCDIV < 0, set it to 0.
    • Adjust SENCYCn to get desired tSAMPLEn according to tSAMPLEn = 128 × (SENCYCn + 1) × 2LCDIV / fSENSORn.
  4. Calibrate gain in the appropriate Registers GAINn (Addresses 0x0E, 0x10, 0x12, 0x14). The gain setting can be used to tune the sensitivity of the touch button. GAINn is a 6-bit field with 64 different gain levels corresponding to normalized gains between 1 and 232. A good mechanical and sensor design typically requires a gain level of around 32 to 50, corresponding to relative gains of 16 to 76 (normalized to gain level of 0). Use the following sequence to determine the appropriate gain for each button:
    • Apply minimum desired force to the button.
    • Read initial DATAn value after the button press. Note that the baseline tracking will affect this value.
    • Calculate gain factor required to increase DATAn to the programmed threshold (default is 160).
    • Look up the Gain Table to find the required gain setting.
  5. Enable special features to mitigate button interference if there is any, in Registers BTPAUSE_MAXWIN, TWIST, COMMON_DEFORM (Addresses 0x16, 0x19, 0x1A).

For more information on inductive touch system design, including mechanical design and sensor electrical design, refer to Inductive Touch System Design Guide.