SBAS661C February   2015  – May 2021 ADS1262 , ADS1263

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and 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: Serial Interface
    7. 7.7 Switching Characteristics: Serial Interface
    8. 7.8 Timing Diagrams
    9. 7.9 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Offset Temperature Drift Measurement
    2. 8.2 Gain Temperature Drift Measurement
    3. 8.3 Common-Mode Rejection Ratio Measurement
    4. 8.4 Power-Supply Rejection Ratio Measurement
    5. 8.5 Crosstalk Measurement (ADS1263)
    6. 8.6 Reference-Voltage Temperature-Drift Measurement
    7. 8.7 Reference-Voltage Thermal-Hysteresis Measurement
    8. 8.8 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  Multifunction Analog Inputs
      2. 9.3.2  Analog Input Description
        1. 9.3.2.1 ESD Diode
        2. 9.3.2.2 Input Multiplexer
      3. 9.3.3  Sensor Bias
      4. 9.3.4  Temperature Sensor
      5. 9.3.5  Power-Supply Monitor
      6. 9.3.6  PGA
      7. 9.3.7  PGA Voltage Overrange Monitors
        1. 9.3.7.1 PGA Differential Output Monitor
        2. 9.3.7.2 PGA Absolute Output-Voltage Monitor
      8. 9.3.8  ADC Reference Voltage
        1. 9.3.8.1 Internal Reference
        2. 9.3.8.2 External Reference
        3. 9.3.8.3 Power-Supply Reference
        4. 9.3.8.4 Low-Reference Monitor
      9. 9.3.9  ADC1 Modulator
      10. 9.3.10 Digital Filter
        1. 9.3.10.1 Sinc Filter Mode
          1. 9.3.10.1.1 Sinc Filter Frequency Response
        2. 9.3.10.2 FIR Filter
        3. 9.3.10.3 50-Hz and 60-Hz Line Cycle Rejection
      11. 9.3.11 Sensor-Excitation Current Sources (IDAC1 and IDAC2)
      12. 9.3.12 Level-Shift Voltage
      13. 9.3.13 General-Purpose Input/Output (GPIO)
      14. 9.3.14 Test DAC (TDAC)
      15. 9.3.15 ADC2 (ADS1263)
        1. 9.3.15.1 ADC2 Inputs
        2. 9.3.15.2 ADC2 PGA
        3. 9.3.15.3 ADC2 Reference
        4. 9.3.15.4 ADC2 Modulator
        5. 9.3.15.5 ADC2 Digital Filter
    4. 9.4 Device Functional Modes
      1. 9.4.1  Conversion Control
        1. 9.4.1.1 Continuous Conversion Mode
        2. 9.4.1.2 Pulse Conversion Mode
        3. 9.4.1.3 ADC2 Conversion Control (ADS1263)
      2. 9.4.2  Conversion Latency
      3. 9.4.3  Programmable Time Delay
      4. 9.4.4  Serial Interface
        1. 9.4.4.1 Chip Select (CS)
        2. 9.4.4.2 Serial Clock (SCLK)
        3. 9.4.4.3 Data Input (DIN)
        4. 9.4.4.4 Data Output/Data Ready (DOUT/DRDY)
        5. 9.4.4.5 Serial Interface Autoreset
      5. 9.4.5  Data Ready Pin (DRDY)
      6. 9.4.6  Conversion Data Software Polling
      7. 9.4.7  Read Conversion Data
        1. 9.4.7.1 Read Data Direct (ADC1 Only)
        2. 9.4.7.2 Read Data by Command
        3. 9.4.7.3 Data-Byte Sequence
          1. 9.4.7.3.1 Status Byte
          2. 9.4.7.3.2 Data Byte Format
          3. 9.4.7.3.3 Checksum Byte (CRC/CHK)
            1. 9.4.7.3.3.1 Checksum Mode (CRC[1:0] = 01h)
          4. 9.4.7.3.4 CRC Mode (CRC[1:0] = 10h)
      8. 9.4.8  ADC Clock Modes
        1. 9.4.8.1 Internal Oscillator
        2. 9.4.8.2 External Clock
        3. 9.4.8.3 Crystal Oscillator
      9. 9.4.9  Calibration
        1. 9.4.9.1 Offset and Full-Scale Calibration
          1. 9.4.9.1.1 Offset Calibration Registers
          2. 9.4.9.1.2 Full-Scale Calibration Registers
        2. 9.4.9.2 ADC1 Offset Self-Calibration (SFOCAL1)
        3. 9.4.9.3 ADC1 Offset System Calibration (SYOCAL1)
        4. 9.4.9.4 ADC2 Offset Self-Calibration ADC2 (SFOCAL2)
        5. 9.4.9.5 ADC2 Offset System Calibration ADC2 (SYOCAL2)
        6. 9.4.9.6 ADC1 Full-Scale System Calibration (SYGCAL1)
        7. 9.4.9.7 ADC2 Full-Scale System Calibration ADC2 (SYGCAL2)
        8. 9.4.9.8 Calibration Command Procedure
        9. 9.4.9.9 User Calibration Procedure
      10. 9.4.10 Reset
        1. 9.4.10.1 Power-On Reset (POR)
        2. 9.4.10.2 RESET/PWDN Pin
        3. 9.4.10.3 Reset by Command
      11. 9.4.11 Power-Down Mode
      12. 9.4.12 Chop Mode
    5. 9.5 Programming
      1. 9.5.1 NOP Command
      2. 9.5.2 RESET Command
      3. 9.5.3 START1, STOP1, START2, STOP2 Commands
      4. 9.5.4 RDATA1, RDATA2 Commands
      5. 9.5.5 SYOCAL1, SYGCAL1, SFOCAL1, SYOCAL2, SYGCAL2, SFOCAL2 Commands
      6. 9.5.6 RREG Command
      7. 9.5.7 WREG Command
    6. 9.6 Register Maps
      1. 9.6.1  Device Identification Register (address = 00h) [reset = x]
      2. 9.6.2  Power Register (address = 01h) [reset = 11h]
      3. 9.6.3  Interface Register (address = 02h) [reset = 05h]
      4. 9.6.4  Mode0 Register (address = 03h) [reset = 00h]
      5. 9.6.5  Mode1 Register (address = 04h) [reset = 80h]
      6. 9.6.6  Mode2 Register (address = 05h) [reset = 04h]
      7. 9.6.7  Input Multiplexer Register (address = 06h) [reset = 01h]
      8. 9.6.8  Offset Calibration Registers (address = 07h, 08h, 09h) [reset = 00h, 00h, 00h]
      9. 9.6.9  Full-Scale Calibration Registers (address = 0Ah, 0Bh, 0Ch) [reset = 40h, 00h, 00h]
      10. 9.6.10 IDACMUX Register (address = 0Dh) [reset = BBh]
      11. 9.6.11 IDACMAG Register (address = 0Eh) [reset = 00h]
      12. 9.6.12 REFMUX Register (address = 0Fh) [reset = 00h]
      13. 9.6.13 TDACP Control Register (address = 10h) [reset = 00h]
      14. 9.6.14 TDACN Control Register (address = 11h) [reset = 00h]
      15. 9.6.15 GPIO Connection Register (address = 12h) [reset = 00h]
      16. 9.6.16 GPIO Direction Register (address = 13h) [reset = 00h]
      17. 9.6.17 GPIO Data Register (address = 14h) [reset = 00h]
      18. 9.6.18 ADC2 Configuration Register (address = 15h) [reset = 00h]
      19. 9.6.19 ADC2 Input Multiplexer Register (address = 16h) [reset = 01h]
      20. 9.6.20 ADC2 Offset Calibration Registers (address = 17h, 18h) [reset = 00h, 00h]
      21. 9.6.21 ADC2 Full-Scale Calibration Registers (address = 19h, 1Ah) [reset = 00h, 40h]
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Isolated (or Floated) Inputs
      2. 10.1.2 Single-Ended Measurements
      3. 10.1.3 Differential Measurements
      4. 10.1.4 Input Range
      5. 10.1.5 Input Filtering
        1. 10.1.5.1 Aliasing
      6. 10.1.6 Input Overload
      7. 10.1.7 Unused Inputs and Outputs
      8. 10.1.8 Voltage Reference
      9. 10.1.9 Serial Interface Connections
    2. 10.2 Typical Application
      1. 10.2.1 3-Wire RTD Measurement with Lead-Wire Compensation
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
        3. 10.2.1.3 Application Curve
    3. 10.3 What To Do and What Not To Do
    4. 10.4 Initialization Setup
  11. 11Power Supply Recommendations
    1. 11.1 Power-Supply Decoupling
    2. 11.2 Analog Power-Supply Clamp
    3. 11.3 Power-Supply Sequencing
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Receiving Notification of Documentation Updates
    2. 13.2 Support Resources
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary

Package Options

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Thermal pad, mechanical data (Package|Pins)
Orderable Information
9.4.7.3.4 CRC Mode (CRC[1:0] = 10h)

In CRC mode, the checksum byte is the 8-bit remainder of the bitwise exclusive-OR (XOR) of the data bytes by a CRC polynomial. For ADC1, use four conversion data bytes in the calculation; for ADC2, use three conversion data bytes. The CRC is based on the CRC-8-ATM (HEC) polynomial: X8 + X2 + X + 1.

The nine binary coefficients of the polynomial are: 100000111. Calculate the CRC by dividing (XOR operation) the data bytes (excluding the CRC) with the polynomial and compare the calculated CRC values to the ADC CRC value. If the values do not match, a data transmission error has occurred. In the event of a data transmission error, read the data again. The CRC provides a higher level of detection of multiple-bit errors.

The following list shows a general procedure to compute the CRC value:

  1. Left shift the initial ADC1 32-bit data value by 8 bits, with zeros padded to the right, creating a new 40-bit data value (the starting data value). For ADC2, left shift the 24-bit value to create a new 32-bit starting data value.
  2. Align the MSB of the CRC polynomial (100000111) to the left-most, logic-one value of the data.
  3. Perform an XOR operation on the data value with the aligned CRC polynomial. The XOR operation creates a new, shorter-length value. The bits of the data values that are not in alignment with the CRC polynomial drop down and append to the right of the new XOR result.
  4. When the XOR result is less than 100h, the procedure ends, yielding the 8-bit CRC value. Otherwise, continue with the XOR operation shown in step 2, using the current data value. The number of loop iterations depends on the value of the initial data.