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

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

9.3.11 Sensor-Excitation Current Sources (IDAC1 and IDAC2)

The ADS1262 and ADS1263 incorporate two, integrated, matched current sources (IDAC1, IDAC2). The current sources provide excitation current to resistive temperature devices (RTDs), thermistors, diodes, and other sensors that require constant current biasing. These devices also contain an internal IDAC multiplexer that provides connection of IDAC1 or IDAC2 to one of the 11 analog pins (AIN0 to AINCOM). The IDACs can be programmed over these current ranges: 50 μA, 100 μA, 250 μA, 500 μA, 750 μA, 1000 μA, 1500 μA, 2000 μA, 2500 μA, and 3000 μA. Figure 9-25 details the IDAC connection. The IDAC switches shown in the diagram are used in the IDAC rotation mode.

GUID-20210423-CA0I-NDCM-L1WN-LT6VDHQSFJSC-low.svg Figure 9-25 IDAC Block Diagram

The internal reference must be enabled for IDAC operation. Take care not to exceed the compliance voltage of the IDACs. In other words, the voltage on the input pin must not exceed VAVDD – 1.1 V; otherwise, the specified accuracy of the IDAC current is not met.

The IDAC currents track the internal reference voltage. As a result of using the same reference voltage for IDAC1 and IDAC2, the current sources are matched. Matched performance is important for applications such as hardware compensated, 3-wire RTDs. IDAC to IDAC mismatch can be improved further by use of the IDAC rotation mode. The rotation mode automatically swaps the IDAC1 and IDAC2 connections of alternate conversions. The ADC averages the alternate conversions to eliminate IDAC mismatch. IDAC rotation can be performed manually by the user (by alternating the IDAC pin connections) or by the IDAC automatic rotation mode. The IDAC rotation sequence is shown as follows:

  • Conversion 1: IDAC1, IDAC2 normal → first output result withheld
  • Conversion 2: IDAC1, IDAC2 rotated positions → Output result 1 = (Conversion 1 + Conversion 2) / 2
  • Conversion 3: IDAC1, IDAC2 normal → Output result 2 = (Conversion 3 + Conversion 2) / 2
  • Conversion 4: IDAC1, IDAC2 rotated positions → Output result 3 = (Conversion 4 + Conversion 3) / 2

The sequence repeats for all succeeding conversions.

In rotation mode, the ADC provides a time delay to allow for settling after the IDAC pin connections are alternated. Note IDAC switching transients may interact with external components that may require additional time to settle. Additional settling time are provided by bits DELAY[3:0] in the MODE0 register. The total delay time results in a reduction of the nominal data rate (see the Section 9.4.2 section). Nevertheless, the existing frequency response nulls provided by the digital filter remain unchanged.