SNOSDD0 December   2021 LDC3114

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1.5 Configuring Button or Raw Data Scan Rate

The LDC3114 periodically samples all active channels at the selected scan rate. The device can operate at eight different scan rates to meet various power consumption requirements, where a lower scan rate achieves lower power consumption.

In Normal Power Mode, the scan rate can be programmed to 80, 40, 20, or 10 SPS through Register NP_SCAN_RATE (Address 0x0D). Additionally through NPFSR bit field in the same register 160 SPS rate can be enabled which overrides the setting of NPSR but not the NPCS bit fields. The NPCS bit field allows to set the part in continuous sampling mode in Normal Power Mode only. When NPCS is set then the settings for NPSR and NPFSR are ignored.

In Low Power Mode, the scan rate can be programmed to 5, 2.5, 1.25, or 0.625 SPS through Register LP_SCAN_RATE (Address 0x0F). The mode is selected by setting the LPWRB pin to VDD (Normal Power) or ground (Low Power). In either mode, each button can be independently enabled through a bit in Register EN (Address 0x0C). Figure 6-9 shows the typical distribution of the scan rates.

Table 8-1 Scan Rates
SCAN RATE (SPS) LPSR (0x0F) SETTING NPSR (0x0D) SETTING NPCS (0x0D) SETTING NPFSR (0x0D) SETTING LPWRB PIN SETTING
0.625 b11 Not Applicable Not Applicable Not Applicable Ground
1.25 b10 Not Applicable Not Applicable Not Applicable Ground
2.5 b01 Not Applicable Not Applicable Not Applicable Ground
5 b00 Not Applicable Not Applicable Not Applicable Ground
10 Not Applicable b11 b0 b0 VDD
20 Not Applicable b10 b0 b0 VDD
40 Not Applicable b01 b0 b0 VDD
80 Not Applicable b00 b0 b0 VDD
160 Not Applicable Not Applicable b0 b1 VDD
Continuous Not Applicable Not Applicable b1 Not Applicable VDD