SBAS590E March   2016  – June 2020 ADS131A02 , ADS131A04


  1. Features
  2. Applications
  3. Description
    1.     Simplified Block Diagram
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions
  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: Asynchronous Interrupt Interface Mode
    7. 7.7  Switching Characteristics: Asynchronous Interrupt Interface Mode
    8. 7.8  Timing Requirements: Synchronous Master Interface Mode
    9. 7.9  Switching Characteristics: Synchronous Master Interface Mode
    10. 7.10 Timing Requirements: Synchronous Slave Interface Mode
    11. 7.11 Switching Characteristics: Synchronous Slave Interface Mode
    12. 7.12 Typical Characteristics
  8. Parameter Measurement Information
    1. 8.1 Noise Measurements
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Clock
        1. XTAL1/CLKIN and XTAL2
        2. ICLK
        3. MODCLK
        4. Data Rate
      2. 9.3.2 Analog Input
      3. 9.3.3 Input Overrange and Underrange Detection
      4. 9.3.4 Reference
      5. 9.3.5 ΔΣ Modulator
      6. 9.3.6 Digital Decimation Filter
      7. 9.3.7 Watchdog Timer
    4. 9.4 Device Functional Modes
      1. 9.4.1 Low-Power and High-Resolution Mode
      2. 9.4.2 Power-Up
      3. 9.4.3 Standby and Wake-Up Mode
      4. 9.4.4 Conversion Mode
      5. 9.4.5 Reset (RESET)
    5. 9.5 Programming
      1. 9.5.1 Interface Protocol
        1. Device Word Length
        2. Fixed versus Dynamic-Frame Mode
        3. Command Word
        4. Status Word
        5. Data Words
          1. ADC Data Word 16-Bit Format
          2. ADC Data Word 24-Bit Format
        6. Hamming Code Error Correction
        7. Cyclic Redundancy Check (CRC)
          1. Computing the CRC
          2. CRC With CRC_MODE = 1
          3. CRC with CRC_MODE = 0
          4. CRC Using the WREGS Command
      2. 9.5.2 SPI Interface
        1. Asynchronous Interrupt Mode
          1. Chip Select (CS)
          2. Serial Clock (SCLK)
          3. Data Input (DIN)
          4. Data Output (DOUT)
          5. Data Ready (DRDY)
          6. Asynchronous Interrupt Mode Data Retrieval
        2. Synchronous Master Mode
          1. Serial Clock (SCLK)
          2. Data Input (DIN)
          3. Data Output (DOUT)
          4. Data Ready (DRDY)
          5. Chip Select (CS)
          6. Synchronous Master Mode Data Retrieval
        3. Synchronous Slave Mode
          1. Chip Select (CS)
          2. Serial Clock (SCLK)
          3. Data Input (DIN)
          4. Data Output (DOUT)
          5. Data Ready (DRDY)
          6. Synchronous Slave Mode Data Retrieval
        4. ADC Frame Complete (DONE)
      3. 9.5.3 SPI Command Definitions
        1.  NULL: Null Command
        2.  RESET: Reset to POR Values
        3.  STANDBY: Enter Standby Mode
        4.  WAKEUP: Exit Standby Mode
        5.  LOCK: Lock ADC Registers
        6.  UNLOCK: Unlock ADC Registers
          1. UNLOCK from POR or RESET
        7.  RREG: Read a Single Register
        8.  RREGS: Read Multiple Registers
        9.  WREG: Write Single Register
        10. WREGS: Write Multiple Registers
    6. 9.6 Register Maps
      1. 9.6.1 User Register Description
        1.  ID_MSB: ID Control Register MSB (address = 00h) [reset = xxh]
          1. Table 16. ID_MSB Register Field Descriptions
        2.  ID_LSB: ID Control Register LSB (address = 01h) [reset = xxh]
          1. Table 17. ID_LSB Register Field Descriptions
        3.  STAT_1: Status 1 Register (address = 02h) [reset = 00h]
          1. Table 18. STAT_1 Register Field Descriptions
        4.  STAT_P: Positive Input Fault Detect Status Register (address = 03h) [reset = 00h]
          1. Table 19. STAT_P Register Field Descriptions
        5.  STAT_N: Negative Input Fault Detect Status Register (address = 04h) [reset = 00h]
          1. Table 20. STAT_N Register Field Descriptions
        6.  STAT_S: SPI Status Register (address = 05h) [reset = 00h]
          1. Table 21. STAT_S Register Field Descriptions
        7.  ERROR_CNT: Error Count Register (address = 06h) [reset = 00h]
          1. Table 22. ERROR_CNT Register Field Descriptions
        8.  STAT_M2: Hardware Mode Pin Status Register (address = 07h) [reset = xxh]
          1. Table 23. STAT_M2 Register Field Descriptions
        9.  Reserved Registers (address = 08h to 0Ah) [reset = 00h]
          1. Table 24. Reserved Registers Field Descriptions
        10. A_SYS_CFG: Analog System Configuration Register (address = 0Bh) [reset = 60h]
          1. Table 25. A_SYS_CFG Register Field Descriptions
        11. D_SYS_CFG: Digital System Configuration Register (address = 0Ch) [reset = 3Ch]
          1. Table 27. D_SYS_CFG Register Field Descriptions
        12. CLK1: Clock Configuration 1 Register (address = 0Dh) [reset = 08h]
          1. Table 28. CLK1 Register Field Descriptions
        13. CLK2: Clock Configuration 2 Register (address = 0Eh) [reset = 86h]
          1. Table 29. CLK2 Register Field Descriptions
        14. ADC_ENA: ADC Channel Enable Register (address = 0Fh) [reset = 00h]
          1. Table 31. ADC_ENA Register Field Descriptions
        15. Reserved Register (address = 10h) [reset = 00h]
          1. Table 32. Reserved Register Field Descriptions
      2. 9.6.2 ADCx: ADC Channel Digital Gain Configuration Registers (address = 11h to 14h) [reset = 00h]
        1. Table 33. ADCx Registers Field Descriptions
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Unused Inputs and Outputs
      2. 10.1.2 Power Monitoring Specific Applications
      3. 10.1.3 Multiple Device Configuration
        1. First Device Configured in Asynchronous Interrupt Mode
        2. First Device Configured in Synchronous Master Mode
        3. All Devices Configured in Synchronous Slave Mode
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curve
    3. 10.3 What To Do and What Not To Do
    4. 10.4 Initialization Set Up
  11. 11Power Supply Recommendations
    1. 11.1 Negative Charge Pump
    2. 11.2 Internal Digital LDO
    3. 11.3 Power-Supply Sequencing
    4. 11.4 Power-Supply Decoupling
  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 Related Links
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Support Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • PBS|32
Thermal pad, mechanical data (Package|Pins)
Orderable Information

SPI Command Definitions

The ADS131A0x device operation is controlled and configured through ten commands. Table 13 summarizes the available commands. The commands are stand-alone, 16-bit words and reside in the first device word of the data frame. Write zeroes to the remaining LSBs when operating in either 24-bit or 32-bit word sizes because each command is 16-bits in length. The commands are decoded following the completion of a data frame and take effect immediately. Each recognized command is acknowledged with a status output in the first device word of the next data frame.

Table 13. Command Definitions

NULL Null command 0000h STATUS
RESET Software reset 0011h READY
STANDBY Enter low-power standby mode 0022h ACK = 0022h
WAKEUP Wake-up from standby mode 0033h ACK = 0033h
LOCK Places the interface in a locked state and ignores all commands except NULL, RREGS, and UNLOCK 0555h ACK = 0555h
UNLOCK Brings the device out of an unconfigured POR state or a locked state 0655h ACK = 0655h
RREG Read a single register at address a aaaa (001a aaaa 0000 0000)b REG
RREGS Read (nnnn nnnn + 1) registers starting at address a aaaa (001a aaaa nnnn nnnn)b RREGS
WREG Write a single register at address a aaaa with data dddd dddd (010a aaaa dddd dddd)b REG (updated register)
WREGS Write (nnnn nnnn + 1) registers beginning at address a aaaa. Additional device words are required to send data (dddd dddd) to register address (a) and data (eeee eeee) to register address (a+1). Each device word contains data for two registers.
The data frame size is extended by (n / 2) device words to allow for command completion.
(011a aaaa nnnn nnnn)b (dddd dddd eeee eeee)b ACK = (010a_aaaa_nnnn_nnnn)b

A command status response is 16 bits in length, located in the MSBs of the first device word in the DOUT data frame. The response indicates that the command in the previous data frame is executed. When operating in 24-bit or 32-bit word size modes, the remaining LSBs of the command status response device word read back as zero unless Hamming code is used. An example showing the acknowledgment to a user input command is shown in Figure 67.

ADS131A02 ADS131A04 User_command_ACK_sbas590.gifFigure 67. User Command Status Response

Some user commands require multiple data words over multiple device frames. This section describes the commands and details which commands require multiple data words.

The command status responses to the user commands are listed in Table 14. Every data frame begins with one of the listed command status responses on DOUT.

Table 14. Command Status Responses

READY Fixed-status word stating that the device is in a power-up ready state or standby mode and is ready for use. The least significant byte of the device word indicates the address 0 hardware device ID code (dd). In the READY state, the device transmits only one word, allowing a 1-word command to be received. An UNLOCK command must be issued before the device responds to other commands. (FFdd)h
ACK Acknowledgment response. The device has received and executed the command and repeats the received command (cccc) as the command status response. (A NULL input does not result in an ACK response). (cccc)h
STATUS/REG Status byte update. Register address a aaaa contains data dddd dddd. This command status response is the response to a recognized RREGS or WREG command.
An automatic status update of register address (02h) is sent when the NULL command is sent.
(001a aaaa dddd dddd)b
RREGS Response for read (nnnn nnnn + 1) registers starting at address a aaaa. Data for two registers are output per device word. If the resulting address extends beyond the usable register space, zeroes are returned for remaining non-existent registers. During an RREGS response, any new input commands are ignored until the RREGS status response completes. (011a aaaa nnnn nnnn)b (dddd dddd eeee eeee)b