JAJSFR6A July   2018  – November 2018 ADS1219

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      電圧、電流、および温度監視アプリケーション
  4. 4 改訂履歴
  5. 5 概要（続き）
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 I2C Timing Requirements
    7. 7.7 I2C Switching Characteristics
    8. 7.8 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Noise Performance
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Multiplexer
      2. 9.3.2 Rail-to-Rail Input Buffers and Programmable Gain Stage
      3. 9.3.3 Voltage Reference
      4. 9.3.4 Modulator and Internal Oscillator
      5. 9.3.5 Digital Filter
      6. 9.3.6 Conversion Times
      7. 9.3.7 Offset Calibration
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power-Up and Reset
        1. 9.4.1.1 Power-On Reset
        2. 9.4.1.2 RESET Pin
        3. 9.4.1.3 Reset by Command
      2. 9.4.2 Conversion Modes
        1. 9.4.2.1 Single-Shot Conversion Mode
        2. 9.4.2.2 Continuous Conversion Mode
      3. 9.4.3 Power-Down Mode
    5. 9.5 Programming
      1. 9.5.1 I2C Interface
        1. 9.5.1.1 I2C Address
        2. 9.5.1.2 Serial Clock (SCL) and Serial Data (SDA)
        3. 9.5.1.3 Data Ready (DRDY)
        4. 9.5.1.4 Interface Speed
        5. 9.5.1.5 Data Transfer Protocol
        6. 9.5.1.6 I2C General Call (Software Reset)
        7. 9.5.1.7 Timeout
      2. 9.5.2 Data Format
      3. 9.5.3 Commands
        1. 9.5.3.1 Command Latching
        2. 9.5.3.2 RESET (0000 011x)
        3. 9.5.3.3 START/SYNC (0000 100x)
        4. 9.5.3.4 POWERDOWN (0000 001x)
        5. 9.5.3.5 RDATA (0001 xxxx)
        6. 9.5.3.6 RREG (0010 0rxx)
        7. 9.5.3.7 WREG (0100 00xx dddd dddd)
      4. 9.5.4 Reading Data and Monitoring for New Conversion Results
    6. 9.6 Register Map
      1. 9.6.1 Configuration and Status Registers
      2. 9.6.2 Register Descriptions
        1. 9.6.2.1 Configuration Register (address = 0h) [reset = 00h]
          1. Table 10. Configuration Register Field Descriptions
        2. 9.6.2.2 Status Register (address = 1h) [reset = 00h]
          1. Table 11. Status Register Field Descriptions
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Interface Connections
      2. 10.1.2 Connecting Multiple Devices on the Same I2C Bus
      3. 10.1.3 Unused Inputs and Outputs
      4. 10.1.4 Analog Input Filtering
      5. 10.1.5 External Reference and Ratiometric Measurements
      6. 10.1.6 Establishing Proper Limits on the Absolute Input Voltage
      7. 10.1.7 Pseudo Code Example
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Voltage Monitoring
        2. 10.2.2.2 High-Side Current Measurement
        3. 10.2.2.3 Thermistor Measurement
        4. 10.2.2.4 Register Settings
      3. 10.2.3 Application Curve
  11. 11Power Supply Recommendations
    1. 11.1 Power-Supply Sequencing
    2. 11.2 Power-Supply Decoupling
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13デバイスおよびドキュメントのサポート
    1. 13.1 デバイス・サポート
      1. 13.1.1 デベロッパー・ネットワークの製品に関する免責事項
    2. 13.2 ドキュメントのサポート
      1. 13.2.1 関連資料
    3. 13.3 ドキュメントの更新通知を受け取る方法
    4. 13.4 コミュニティ・リソース
    5. 13.5 商標
    6. 13.6 静電気放電に関する注意事項
    7. 13.7 Glossary
  14. 14メカニカル、パッケージ、および注文情報

10.1.4 Analog Input Filtering

Analog input filtering serves two purposes:

  • Limits the effect of aliasing during the ADC sampling process
  • Attenuates unwanted noise components outside the bandwidth of interest

In most cases, a first-order resistor capacitor (RC) filter is sufficient to completely eliminate aliasing or to reduce the effect of aliasing to a level within the noise floor of the sensor. A good starting point for a system design with the ADS1219 is to use a differential RC filter with a cutoff frequency set somewhere between the selected output data rate and 25 kHz. Make the series resistor values as small as possible to reduce voltage drops across the resistors caused by the device input currents to a minimum. However, the resistors should be large enough to limit the current into the analog inputs to less than 10 mA in the event of an overvoltage. Then choose the differential capacitor value to achieve the target filter cutoff frequency. Common-mode filter capacitors to GND can be added as well, but should always be at least ten times smaller than the differential filter capacitor.

Internal to the device, prior to the buffer inputs, is an EMI filter. The cutoff frequency of this filter is approximately 31.8 MHz, which helps reject high-frequency interferences.