SBASA22A september   2022  – july 2023 ADS131B26-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Timing Diagram
    9. 6.9 Typical Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Offset Drift Measurement
    2. 7.2 Gain Drift Measurement
    3. 7.3 Noise Performance
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Naming Conventions
      2. 8.3.2 Precision Voltage References (REFA, REFB)
      3. 8.3.3 Clocking (MCLK, OSCM, OSCD)
      4. 8.3.4 ADC1y
        1. 8.3.4.1 ADC1y Input Multiplexer
        2. 8.3.4.2 ADC1y Programmable Gain Amplifier (PGA)
        3. 8.3.4.3 ADC1y ΔΣ Modulator
        4. 8.3.4.4 ADC1y Digital Filter
        5. 8.3.4.5 ADC1y Offset and Gain Calibration
        6. 8.3.4.6 ADC1y Conversion Data
      5. 8.3.5 ADC2y
        1. 8.3.5.1 ADC2y Input Multiplexer
        2. 8.3.5.2 ADC2y Programmable Gain Amplifier (PGA)
        3. 8.3.5.3 ADC2y ΔΣ Modulator
        4. 8.3.5.4 ADC2y Digital Filter
        5. 8.3.5.5 ADC2y Offset and Gain Calibration
        6. 8.3.5.6 ADC2y Sequencer
        7. 8.3.5.7 VCMy Buffers
        8. 8.3.5.8 ADC2y Measurement Configurations
        9. 8.3.5.9 ADC2y Conversion Data
      6. 8.3.6 ADC3y
      7. 8.3.7 General-Purpose Digital Inputs and Outputs (GPIO0 to GPIO4)
        1. 8.3.7.1 GPIOx PWM Output Configuration
        2. 8.3.7.2 GPIOx PWM Input Readback
      8. 8.3.8 General-Purpose Digital Inputs and Outputs (GPIO0A, GPIO1A, GPIO0B, GPIO1B)
      9. 8.3.9 Monitors and Diagnostics
        1. 8.3.9.1  Supply Monitors
        2. 8.3.9.2  Clock Monitors
        3. 8.3.9.3  Digital Monitors
          1. 8.3.9.3.1 Register Map CRC
          2. 8.3.9.3.2 Memory Map CRC
          3. 8.3.9.3.3 GPIO Readback
        4. 8.3.9.4  Communication Monitors
        5. 8.3.9.5  Fault Flags and Fault Masking
        6. 8.3.9.6  FAULT Pin
        7. 8.3.9.7  Diagnostics and Diagnostic Procedure
        8. 8.3.9.8  Indicators
        9. 8.3.9.9  Conversion and Sequence Counters
        10. 8.3.9.10 Supply Voltage Readback
        11. 8.3.9.11 Temperature Sensors (TSA, TSB)
        12. 8.3.9.12 Test DACs (TDACA, TDACB)
        13. 8.3.9.13 Open-Wire Detection
        14. 8.3.9.14 Missing Host Detection and MHD Pin
        15. 8.3.9.15 Overcurrent Comparators (OCCA, OCCB)
          1. 8.3.9.15.1 OCCA and OCCB Pins
          2. 8.3.9.15.2 Overcurrent Indication Response Time
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Up and Reset
        1. 8.4.1.1 Power-On Reset (POR)
        2. 8.4.1.2 RESETn Pin
        3. 8.4.1.3 RESET Command
      2. 8.4.2 Operating Modes
        1. 8.4.2.1 Active Mode
        2. 8.4.2.2 Standby Mode
        3. 8.4.2.3 Power-Down Mode
      3. 8.4.3 ADC Conversion Modes
        1. 8.4.3.1 ADC1y and ADC3y Conversion Modes
          1. 8.4.3.1.1 Continuous-Conversion Mode
          2. 8.4.3.1.2 Single-Shot Conversion Mode
          3. 8.4.3.1.3 Global-Chop Mode
            1. 8.4.3.1.3.1 Overcurrent Indication Response Time in Global-Chop Mode
        2. 8.4.3.2 ADC2y Sequencer Operation and Sequence Modes
          1. 8.4.3.2.1 Continuous Sequence Mode
          2. 8.4.3.2.2 Single-Shot Sequence Mode
          3. 8.4.3.2.3 Synchronized Single-Shot Sequence Mode Based on ADC1y Conversion Starts
    5. 8.5 Programming
      1. 8.5.1 Serial Interface
        1. 8.5.1.1 Serial Interface Signals
          1. 8.5.1.1.1 Chip Select (CSn)
          2. 8.5.1.1.2 Serial Data Clock (SCLK)
          3. 8.5.1.1.3 Serial Data Input (SDI)
          4. 8.5.1.1.4 Serial Data Output (SDO)
          5. 8.5.1.1.5 Data Ready (DRDYn)
        2. 8.5.1.2 Serial Interface Communication Structure
          1. 8.5.1.2.1 SPI Communication Frames
          2. 8.5.1.2.2 SPI Communication Words
          3. 8.5.1.2.3 STATUS Word
          4. 8.5.1.2.4 Communication Cyclic Redundancy Check (CRC)
          5. 8.5.1.2.5 Commands
            1. 8.5.1.2.5.1 NULL (0000 0000 0000 0000b)
            2. 8.5.1.2.5.2 RESET (0000 0000 0001 0001b)
            3. 8.5.1.2.5.3 LOCK (0000 0101 0101 0101b)
            4. 8.5.1.2.5.4 UNLOCK (0000 0110 0101 0101b)
            5. 8.5.1.2.5.5 WREG (011a aaaa aaa0 0nnnb)
            6. 8.5.1.2.5.6 RREG (101a aaaa aaan nnnnb)
          6. 8.5.1.2.6 SCLK Counter
          7. 8.5.1.2.7 SPI Timeout
          8. 8.5.1.2.8 Reading ADC1A, ADC1B, ADC2A, ADC2B, ADC3A, and ADC3B Conversion Data
          9. 8.5.1.2.9 DRDYn Pin Behavior
    6. 8.6 Register Map
      1. 8.6.1 Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Unused Inputs and Outputs
      2. 9.1.2 Minimum Interface Connections
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Current-Shunt Measurement
        2. 9.2.2.2 Battery-Pack Voltage Measurement
        3. 9.2.2.3 Other Voltage Measurements
        4. 9.2.2.4 Shunt Temperature Measurement
        5. 9.2.2.5 Analog Output Temperature Sensor Measurement
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Power-Supply Options
        1. 9.3.1.1 Single Unregulated External 4-V to 16-V Supply (3.3-V Digital I/O Levels)
        2. 9.3.1.2 Single Regulated External 3.3-V Supply (3.3-V Digital IO Levels)
        3. 9.3.1.3 Single Regulated External 5-V Supply (5-V Digital I/O Levels)
      2. 9.3.2 Power-Supply Sequencing
      3. 9.3.3 Power-Supply Decoupling
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
8.4.3.1.3 Global-Chop Mode

The signal chains of ADC1y and ADC3y use a very low-drift, chopper-stabilized PGA and ΣΔ-modulator to provide very low offset error and offset drift. However, a small amount of offset drift remains in normal measurement. For that reason, the ADC1y and ADC3y signal chains incorporate an optional global-chop mode to reduce offset error and offset drift over both temperature and time to exceptionally low levels. When the global-chop mode is enabled by setting the GC13y_EN bit, ADC1y and ADC3y perform two consecutive conversions with alternate input signal polarity to cancel offset error. The first conversion is taken with normal input polarity. The global-chop control logic inverts the input polarity and resets the digital filter for the second conversion. The average of the two conversions yields the final corrected result, removing the offset voltage. Figure 8-19 illustrates a block diagram of the ADC1y global-chop implementation. VOFS models the combined PGA and ADC1y internal offset voltage. Only this device-inherent offset voltage is reduced by global-chop mode. Offset in the external circuitry connected to the analog inputs is not affected by global-chop mode. The GC13y_EN bit enables global-chop mode for both ADC1y and ADC3y.

GUID-20221012-SS0I-S19B-LTQC-D97CFFGJZV6P-low.svg Figure 8-19 ADC1y Global-Chop Mode Control Diagram

The operational sequence of global-chop mode is as follows:

  • Conversion C1: VCPA – VCNA – VOFS → First conversion withheld after conversion start
  • Conversion C2: VCNA – VCPA – VOFS → Output 1 = (VC1 – VC2) / 2 = VCPA – VCNA
  • Conversion C3: VCPA – VCNA – VOFS → Output 2 = (VC3 – VC2) / 2 = VCPA – VCNA
  • ...

The first conversion result (Output 1) after a conversion start is available after ADC1y takes two settled conversions. Because of the sinc3 filter, data of one conversion settles in three conversions cycles. Equation 20 calculates the time required to output the first conversion result after a conversion start.

In continuous-conversion mode with the global-chop mode enabled, subsequent conversions complete in tGC_DATA, as calculated by Equation 21 and shown in Figure 8-20. That means the data rate in global-chop mode is approximately 1/3rd the data rate in normal mode.

Equation 20. tGC_SETTLE = 2 × (tGC13y_DELAY + 3 × OSR × tMOD) + 44 tMOD
Equation 21. tGC_DATA = tGC13A_DELAY + 3 × OSR × tMOD,

Before starting conversions after the input polarity is inverted, ADC1y waits the global-chop delay time, GC13y_DELAY[2:0], to allow for the internal circuitry to settle. In some cases, the programmable global-chop delay time must be increased to allow for settling of external components.

GUID-20221011-SS0I-SSJT-WBJP-HHQR9K4FGGV7-low.svg Figure 8-20 Sinc3 Filter Settling Time and Conversion Period in Global-Chop Mode

Global-chop mode reduces the ADC1y and ADC3y noise by a factor of √2 because two conversions are averaged. Divide the input-referred noise values in Table 7-1 and Table 7-3 by √2 to derive the noise performance when global-chop mode is enabled.

The notches of the sinc3 filter in Figure 8-3 do not change in global-chop mode. However, additional filter notches appear at multiples of fGC_DATA / 2.