SBAS705B June   2015  – April 2020 ADS131E08S

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Power Application: Three-Phase Voltage and Current Connection
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  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 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Noise Measurements
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Electromagnetic Interference (EMI) Filter
      2. 9.3.2  Input Multiplexer
        1. 9.3.2.1 Device Noise Measurements
        2. 9.3.2.2 Test Signals (TestP and TestN)
        3. 9.3.2.3 Temperature Sensor (TempP, TempN)
        4. 9.3.2.4 Power-Supply Measurements (MVDDP, MVDDN)
      3. 9.3.3  Analog Input
      4. 9.3.4  PGA Settings and Input Range
        1. 9.3.4.1 Input Common-Mode Range
      5. 9.3.5  ΔΣ Modulator
      6. 9.3.6  Clock
      7. 9.3.7  Digital Decimation Filter
      8. 9.3.8  Voltage Reference
      9. 9.3.9  Input Out-of-Range Detection
      10. 9.3.10 General-Purpose Digital I/O (GPIO)
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power-Down
      2. 9.4.2 Reset
      3. 9.4.3 Conversion Mode
        1. 9.4.3.1 START Pin Low-to-High Transition or START Command Sent
        2. 9.4.3.2 Input Signal Step
        3. 9.4.3.3 Continuous Conversion Mode
    5. 9.5 Programming
      1. 9.5.1 SPI Interface
        1. 9.5.1.1 Chip Select (CS)
        2. 9.5.1.2 Serial Clock (SCLK)
        3. 9.5.1.3 Data Input (DIN)
        4. 9.5.1.4 Data Output (DOUT)
        5. 9.5.1.5 Data Ready (DRDY)
      2. 9.5.2 Data Retrieval
        1. 9.5.2.1 Status Word
        2. 9.5.2.2 Readback Length
        3. 9.5.2.3 Data Format
      3. 9.5.3 SPI Command Definitions
        1. 9.5.3.1  WAKEUP: Exit STANDBY Mode
        2. 9.5.3.2  STANDBY: Enter STANDBY Mode
        3. 9.5.3.3  RESET: Reset Registers to Default Values
        4. 9.5.3.4  START: Start Conversions
        5. 9.5.3.5  STOP: Stop Conversions
        6. 9.5.3.6  OFFSETCAL: Channel Offset Calibration
        7. 9.5.3.7  RDATAC: Start Read Data Continuous Mode
        8. 9.5.3.8  SDATAC: Stop Read Data Continuous Mode
        9. 9.5.3.9  RDATA: Read Data
        10. 9.5.3.10 RREG: Read from Register
        11. 9.5.3.11 WREG: Write to Register
        12. 9.5.3.12 Sending Multibyte Commands
    6. 9.6 Register Map
      1. 9.6.1 Register Descriptions
        1. 9.6.1.1 ID: ID Control Register (Factory-Programmed, Read-Only) (address = 00h) [reset = D2h]
          1. Table 11. ID: ID Control Register Field Descriptions
        2. 9.6.1.2 CONFIG1: Configuration Register 1 (address = 01h) [reset = 94h]
          1. Table 12. CONFIG1: Configuration Register 1 Field Descriptions
        3. 9.6.1.3 CONFIG2: Configuration Register 2 (address = 02h) [reset = 00h]
          1. Table 14. CONFIG2: Configuration Register 2 Field Descriptions
        4. 9.6.1.4 CONFIG3: Configuration Register 3 (address = 03h) [reset = E0h]
          1. Table 15. CONFIG3: Configuration Register 3 Field Descriptions
        5. 9.6.1.5 FAULT: Fault Detect Control Register (address = 04h) [reset = 00h]
          1. Table 16. FAULT: Fault Detect Control Register Field Descriptions
        6. 9.6.1.6 CHnSET: Individual Channel Settings (address = 05h to 0Ch) [reset = 10h]
          1. Table 17. CHnSET: Individual Channel Settings Field Descriptions
        7. 9.6.1.7 FAULT_STATP: Fault Detect Positive Input Status (address = 12h) [reset = 00h]
          1. Table 18. FAULT_STATP: Fault Detect Positive Input Status Field Descriptions
        8. 9.6.1.8 FAULT_STATN: Fault Detect Negative Input Status (address = 13h) [reset = 00h]
          1. Table 19. FAULT_STATN: Fault Detect Negative Input Status Field Descriptions
        9. 9.6.1.9 GPIO: General-Purpose IO Register (address = 14h) [reset = 0Fh]
          1. Table 20. GPIO: General-Purpose IO Register Field Descriptions
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Multiple Device Configuration
        1. 10.1.1.1 Synchronizing Multiple Devices
        2. 10.1.1.2 Standard Configuration
        3. 10.1.1.3 Daisy-Chain Configuration
      2. 10.1.2 Power Monitoring Specific Applications
      3. 10.1.3 Current Sensing
      4. 10.1.4 Voltage Sensing
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curves
    3. 10.3 Initialization Set Up
      1. 10.3.1 Setting the Device Up for Basic Data Capture
  11. 11Power Supply Recommendations
    1. 11.1 Power-Up Timing
    2. 11.2 Recommended External Capacitor Values
    3. 11.3 Device Connections for Unipolar Power Supplies
    4. 11.4 Device Connections for Bipolar Power Supplies
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Support Resources
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

9.3.8 Voltage Reference

The ADS131E08S uses an internal voltage reference and does not provide the option of connecting an external reference voltage. Figure 29 shows a simplified block diagram of the internal reference. There are two internal reference voltage options generated with respect to AVSS: 2.4 V and 4 V. Connect VREFN to AVSS.

ADS131E08S ai_int_ref_bas705.gif
1. For VREF = 2.4 V: R1 = 12.5 kΩ, R2 = 25 kΩ, and R3 = 25 kΩ.
For VREF = 4 V: R1 = 10.5 kΩ, R2 = 15 kΩ, and R3 = 35 kΩ.
Figure 29. Internal Reference Implementation

The external band-limiting capacitors, connected to VCAP1 and between the VREFP and VREFN nodes, determine the amount of reference noise contribution. Although limiting the bandwidth through larger capacitor sizes helps keep noise at a minimum, using large capacitors increases the power-up time of the ADC. Using the capacitor values shown in Figure 29 is recommended to optimize the power-up time of the device.

The internal band gap (VCAP1 pin) used to create the internal reference voltage requires a capacitor to filter noise. As a result of limited drive strength, the size of the capacitor on VCAP1 sets the power-up time of the device. Figure 30 shows the accuracy of the first 200 conversion samples with different capacitors on VCAP1 following power-up. Larger capacitors on VCAP1 help filter broadband noise but add to the power-up time. To generate the plot of Figure 30, the ADC input voltage is fixed at 1 V during power-up and the ADC output conversion result is tracked to show the VCAP1 power-up time.

ADS131E08S D016_sbas705.gif
Figure 30. VCAP1 Power-Up Time versus External Capacitor Value

Use the VREF_4V bit in the CONFIG2 register to set the internal reference to either 4 V or 2.4 V. By default, the reference powers up as 4 V for a 5-V system (or ±2.5-V supplies). In a 3-V system (or ±1.5-V supplies), configure the internal reference to 2.4 V immediately following power-up. No damage occurs to the device when the ADS131E08S is set to a 4-V reference when using a 3-V supply system. The internal reference saturates until programmed to 2.4 V.