JAJSDO0B May   2017  – October 2018 ADS122U04

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 UART Timing Requirements
    7. 7.7 UART 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
      14. 9.3.14 General-Purpose Digital Inputs/Outputs
    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 UART Interface
        1. 9.5.1.1 Receive (RX)
        2. 9.5.1.2 Transmit (TX)
        3. 9.5.1.3 Data Ready (DRDY)
        4. 9.5.1.4 Protocol
        5. 9.5.1.5 Timeout
      2. 9.5.2 Data Format
      3. 9.5.3 Commands
        1. 9.5.3.1 RESET (0000 011x)
        2. 9.5.3.2 START/SYNC (0000 100x)
        3. 9.5.3.3 POWERDOWN (0000 001x)
        4. 9.5.3.4 RDATA (0001 xxxx)
        5. 9.5.3.5 RREG (0010 rrrx)
        6. 9.5.3.6 WREG (0100 rrrx dddd dddd)
        7. 9.5.3.7 Command Latching
      4. 9.5.4 Reading Data
        1. 9.5.4.1 Manual Data Read Mode
        2. 9.5.4.2 Automatic Data Read Mode
      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 18. Configuration Register 0 Field Descriptions
        2. 9.6.2.2 Configuration Register 1 (address = 01h) [reset = 00h]
          1. Table 19. Configuration Register 1 Field Descriptions
        3. 9.6.2.3 Configuration Register 2 (address = 02h) [reset = 00h]
          1. Table 21. Configuration Register 2 Field Descriptions
        4. 9.6.2.4 Configuration Register 3 (address = 03h) [reset = 00h]
          1. Table 22. Configuration Register 3 Field Descriptions
        5. 9.6.2.5 Configuration Register 4 (address = 04h) [reset = 00h]
          1. Table 23. Configuration Register 4 Field Descriptions
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Interface Connections
      2. 10.1.2 Analog Input Filtering
      3. 10.1.3 External Reference and Ratiometric Measurements
      4. 10.1.4 Establishing Proper Limits on the Absolute Input Voltage
      5. 10.1.5 Unused Inputs and Outputs
      6. 10.1.6 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 ドキュメントのサポート
      1. 13.1.1 関連資料
    2. 13.2 ドキュメントの更新通知を受け取る方法
    3. 13.3 コミュニティ・リソース
    4. 13.4 商標
    5. 13.5 静電気放電に関する注意事項
    6. 13.6 Glossary
  14. 14メカニカル、パッケージ、および注文情報

10.1.6 Pseudo Code Example

The following list shows a pseudo code sequence with the required steps to set up the device and the microcontroller that interfaces to the ADC in order to take subsequent readings from the ADS122U04 in continuous conversion mode. The dedicated GPIO2/DRDY pin is used to indicate availability of new conversion data. The default configuration register settings are changed to gain = 16, continuous conversion mode. This example shows data collection using manual data read mode.


Power-up; Delay to allow power supplies to settle and power-on reset to complete; minimum of 600 µs; Configure the UART interface of the microcontroller to 8-N-1 format; Configure the microcontroller GPIO connected to the GPIO2/DRDY pin as a falling edge triggered interrupt input; Send the synchronization word to the device (55h); Send the RESET command (06h) to make sure the device is properly reset after power-up; Delay for a minimum of td(RSRX); Write the respective register configurations with the WREG command, sending the synchronization word each time (55h, 40h, 08h, 55h, 42h, 08h, 55h, 48h, 48h); As an optional sanity check, send the synchronization word then read back all configuration registers with the RREG command (55h, 2xh); Send the synchronization word to the device (55h); Send the START/SYNC command (08h) to start converting in continuous conversion mode; Loop { Wait for GPIO2/DRDY to transition low; Send the synchronization word (55h); Send the RDATA command (10h); Receive 3 bytes of data from TX; } Send the synchronization word (55h); Send the POWERDOWN command (02h) to stop conversions and put the device in power-down mode;

TI recommends running an offset calibration before performing any measurements or when changing the gain of the PGA. The internal offset of the device can, for example, be measured by shorting the inputs to mid-supply (MUX[3:0] = 1110). The microcontroller then takes multiple readings from the device with the inputs shorted and stores the average value in the microcontroller memory. When measuring the sensor signal, the microcontroller then subtracts the stored offset value from each device reading to obtain an offset compensated result; the offset can be either positive or negative in value.