SBAS778B June   2017  – August 2019 ADS1287

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Functional Block Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 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 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Noise Performance
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input and Multiplexer
      2. 8.3.2 Programmable Gain Amplifier (PGA)
      3. 8.3.3 Modulator
        1. 8.3.3.1 Modulator Overrange
      4. 8.3.4 Voltage Reference Inputs (REFP, REFN)
      5. 8.3.5 Digital Filter
        1. 8.3.5.1 Sinc Filter Stage
        2. 8.3.5.2 FIR Filter Stage
        3. 8.3.5.3 Group Delay and Step Response
          1. 8.3.5.3.1 Linear Phase Response
          2. 8.3.5.3.2 Minimum Phase Response
        4. 8.3.5.4 HPF Stage
      6. 8.3.6 Reset (RESET Pin and Reset Command)
      7. 8.3.7 Master Clock Input (CLK)
    4. 8.4 Device Functional Modes
      1. 8.4.1  Operational Mode
      2. 8.4.2  Chop Mode
      3. 8.4.3  Offset
      4. 8.4.4  Power-Down Mode
      5. 8.4.5  Standby Mode
      6. 8.4.6  Synchronization
        1. 8.4.6.1 Pulse-Sync Mode
        2. 8.4.6.2 Continuous-Sync Mode
      7. 8.4.7  Reading Data
        1. 8.4.7.1 Read-Data-Continuous Mode (RDATAC)
        2. 8.4.7.2 Stop-Read-Data-Continuous-Mode (SDATAC)
      8. 8.4.8  Conversion Data Format
      9. 8.4.9  Offset and Full-Scale Calibration Registers
        1. 8.4.9.1 OFC[2:0] Registers
        2. 8.4.9.2 FSC[2:0] Registers
      10. 8.4.10 Calibration Command
        1. 8.4.10.1 OFSCAL Command
        2. 8.4.10.2 GANCAL Command
      11. 8.4.11 User Calibration
    5. 8.5 Programming
      1. 8.5.1 Serial Interface
        1. 8.5.1.1 Chip Select (CS)
        2. 8.5.1.2 Serial Clock (SCLK)
        3. 8.5.1.3 Data Input (DIN)
        4. 8.5.1.4 Data Output (DOUT)
        5. 8.5.1.5 Serial Interface Timeout
        6. 8.5.1.6 Data Ready (DRDY)
      2. 8.5.2 Commands
        1. 8.5.2.1  WAKEUP: Wake Up Command
        2. 8.5.2.2  STANDBY: Standby Mode Command
        3. 8.5.2.3  SYNC: Synchronize ADC Conversions
        4. 8.5.2.4  RESET: Reset Command
        5. 8.5.2.5  RDATAC: Read Data Continuous Mode Command
        6. 8.5.2.6  SDATAC: Stop Read Data Continuous Mode Command
        7. 8.5.2.7  RDATA: Read Data Command
        8. 8.5.2.8  RREG: Read Register Data Command
        9. 8.5.2.9  WREG: Write Register Data Command
        10. 8.5.2.10 OFSCAL: Offset Calibration Command
        11. 8.5.2.11 GANCAL: Gain Calibration Command
    6. 8.6 Register Map
      1. 8.6.1 Register Descriptions
        1. 8.6.1.1 ID/CFG: ID, Configuration Register (address = 00h) [reset = x0h]
          1. Table 22. ID/CFG Register Field Descriptions
        2. 8.6.1.2 CONFIG0: Configuration Register 0 (address = 01h) [reset = 52h]
          1. Table 23. CONFIG0 Register Field Descriptions
        3. 8.6.1.3 CONFIG1: Configuration Register 1 (address = 02h) [reset = 08h]
          1. Table 24. CONFIG1 Register Field Descriptions
        4. 8.6.1.4 High-Pass Filter Corner Frequency (HPFx) Registers (address = 03h, 04h) [reset = 32h, 03h]
          1. Table 25. HPF0, HPF1 Registers Field Description
        5. 8.6.1.5 Offset Calibration (OFCx) Registers (address = 05h, 06h, 07h) [reset = 00h, 00h, 00h]
          1. Table 26. OFC0, OFC1, OFC2 Registers Field Description
        6. 8.6.1.6 Full-Scale Calibration (FSCx) Registers (address = 08h, 09h, 0Ah) [reset = 00h, 00h, 40h]
          1. Table 27. FSC0, FSC1, FSC2 Registers Field Description
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Geophone Application
      2. 9.2.2 Digital Interface
    3. 9.3 Initialization Set Up
  10. 10Power Supply Recommendations
    1. 10.1 Analog Power Supplies
    2. 10.2 Digital Power Supply
    3. 10.3 Power-Supply Sequence
  11. 11Layout
    1. 11.1 Layout Guidelines
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.4.10 Calibration Command

The calibration commands (OFSCAL or GANCAL) perform calibration on demand. These commands compute the offset and gain correction register factors, respectively. The appropriate calibration voltage must be applied for calibration. Low data rates are able to provide more consistent calibration results resulting from lower noise compared to high data rates. If calibrating at system power-on, be sure the reference voltage is fully settled. Calibration is not available when operating in the sinc filter mode.

Figure 62 shows the calibration command sequence. Apply the appropriate calibration voltage to the ADC. After the input voltage stabilizes, send the SDATAC, SYNC, and RDATAC commands in sequence (allow 24 / fCLK gaps between commands). DRDY is then driven low 64 data periods later. After DRDY is driven low, send the SDATAC command, then the calibration command (OFSCAL or GANCAL), followed by the RDATAC command. After 16 data periods, calibration completion is indicated when DRDY is driven low. The calibrated conversion data are available at this time. The SYNC input must remain high during the calibration sequence.

ADS1287 tim_off_gan_cali_bas418.gifFigure 62. Calibration Command Sequence