JAJSF20B October   2017  – October 2018 ADS122C04

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      Kタイプ熱電対温度の測定
  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  Low-Noise Programmable Gain Stage
        1. 9.3.2.1 PGA Input Voltage Requirements
        2. 9.3.2.2 Bypassing the PGA
      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  Excitation Current Sources
      8. 9.3.8  Sensor Detection
      9. 9.3.9  System Monitor
      10. 9.3.10 Temperature Sensor
        1. 9.3.10.1 Converting From Temperature to Digital Codes
          1. 9.3.10.1.1 For Positive Temperatures (For Example, 50°C):
          2. 9.3.10.1.2 For Negative Temperatures (For Example, –25°C):
        2. 9.3.10.2 Converting From Digital Codes to Temperature
      11. 9.3.11 Offset Calibration
      12. 9.3.12 Conversion Data Counter
      13. 9.3.13 Data Integrity Features
    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 Operating Modes
        1. 9.4.3.1 Normal Mode
        2. 9.4.3.2 Turbo Mode
        3. 9.4.3.3 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 rrxx)
        7. 9.5.3.7 WREG (0100 rrxx dddd dddd)
      4. 9.5.4 Reading Data and Monitoring for New Conversion Results
      5. 9.5.5 Data Integrity
    6. 9.6 Register Map
      1. 9.6.1 Configuration Registers
      2. 9.6.2 Register Descriptions
        1. 9.6.2.1 Configuration Register 0 (address = 00h) [reset = 00h]
          1. Table 19. Configuration Register 0 Field Descriptions
        2. 9.6.2.2 Configuration Register 1 (address = 01h) [reset = 00h]
          1. Table 20. Configuration Register 1 Field Descriptions
        3. 9.6.2.3 Configuration Register 2 (address = 02h) [reset = 00h]
          1. Table 22. Configuration Register 2 Field Descriptions
        4. 9.6.2.4 Configuration Register 3 (address = 03h) [reset = 00h]
          1. Table 23. Configuration Register 3 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 Applications
      1. 10.2.1 K-Type Thermocouple Measurement (–200°C to +1250°C)
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
        3. 10.2.1.3 Application Curves
      2. 10.2.2 3-Wire RTD Measurement (–200°C to +850°C)
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
          1. 10.2.2.2.1 Design Variations for 2-Wire and 4-Wire RTD Measurements
        3. 10.2.2.3 Application Curves
      3. 10.2.3 Resistive Bridge Measurement
        1. 10.2.3.1 Design Requirements
        2. 10.2.3.2 Detailed Design Procedure
  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

9.3.7 Excitation Current Sources

The device provides two matched programmable excitation current sources (IDACs) for resistance temperature detector (RTD) applications. The output current of the current sources can be programmed to 10 µA, 50 µA, 100 µA, 250 µA, 500 µA, 1000 µA, or 1500 µA using the respective bits (IDAC[2:0]) in the configuration register. Each current source can be connected to any of the analog inputs (AINx) as well as to the dedicated reference inputs (REFP and REFN). Both current sources can also be connected to the same pin. Routing of the IDACs is configured by bits (I1MUX[2:0], I2MUX[2:0]) in the configuration register. Care must be taken not to exceed the compliance voltage of the IDACs. In other words, limit the voltage on the pin where the IDAC is routed to ≤ (AVDD – 0.9 V), otherwise the specified accuracy of the IDAC current is not met. For three-wire RTD applications, the matched current sources can be used to cancel errors caused by sensor lead resistance (see the 3-Wire RTD Measurement section for more details).

The IDACs require up to 200 µs to start up after the IDAC current is programmed to the respective value using the IDAC[2:0] bits. Set the IDAC current to the respective value using the IDAC[2:0] bits and then select the routing for each IDAC (I1MUX[2:0], I2MUX[2:0]) thereafter.

In single-shot conversion mode, the IDACs remain active between any two conversions if the IDAC[2:0] bits are set to a value other than 000. However, the IDACs are powered down whenever the POWERDOWN command is issued.

Keep in mind that the analog supply current increases when enabling the IDACs (that is, when the IDAC[2:0] bits are set to a value other than 000). The IDAC circuit needs this bias current to operate even when the IDACs are not routed to any pin (I1MUX[2:0] = I2MUX[2:0] = 000). In addition, the selected output current is drawn from the analog supply when I1MUX[2:0] or I2MUX[2:0] are set to a value other than 000.