SBAU435 February   2024 ADS127L18

 

  1.   1
  2.   Description
  3.   Get Started
  4.   Features
  5.   Applications
  6.   6
  7. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  8. 2Hardware
    1. 2.1  EVM Analog Input Options
    2. 2.2  Power Requirements
    3. 2.3  ADC Connections and Decoupling
    4. 2.4  ADC Input Amplifiers
    5. 2.5  VCOM Buffer
    6. 2.6  Voltage Reference
    7. 2.7  Reference Buffer
    8. 2.8  Clock Tree
    9. 2.9  Serial Interface
    10. 2.10 EEPROM
    11. 2.11 Power Supplies
    12. 2.12 Low Dropout Regulator (LDO)
  9. 3Software
    1. 3.1 Software Description
    2. 3.2 ADS127L18 EVM Software Installation
  10. 4Implementation Results
    1. 4.1 EVM Operation
      1. 4.1.1 Evaluation Setup
      2. 4.1.2 Optional EVM Connections
      3. 4.1.3 EVM Register Settings
      4. 4.1.4 ADC Capture Settings
        1. 4.1.4.1 ADC Configuration
        2. 4.1.4.2 Clocking Configuration
        3. 4.1.4.3 SPI and Data Port Configuration
        4. 4.1.4.4 Filter Configuration
        5. 4.1.4.5 Channel Configuration
      5. 4.1.5 Time Domain Display
      6. 4.1.6 Spectral Analysis Display
      7. 4.1.7 Histogram Analysis Display
  11. 5Hardware Design Files
    1. 5.1 Schematics
    2. 5.2 PCB Layouts
    3. 5.3 Bill of Materials (BOM)
  12. 6Additional Information
    1. 6.1 Trademarks
  13. 7Related Documentation
    1. 7.1 Supplemental Content

2.6 Voltage Reference

Figure 3-6 shows the REF6225 and REF7040 configuration. By default, the REF6225 is connected to the ADS127L18 through the 0Ω resistor R62. The REF6225 includes an integrated wide bandwidth buffer that is capable of driving the switched-capacitor input to the ADS127L18 without the need for an additional buffer. The REF6225 is sufficient to meet the ADS127L18 data sheet specifications for dynamic performance.

The REF7040 is not populated, but can be added to the board if needed. The REF7040 can be configured to directly drive the ADS127L18 reference input by removing resistor R62 and populating resistor R63. This option provides good DC performance, but AC performance is not the best. For best AC and DC performance using the REF7040, the external reference buffer can be used. Please refer to Section 2.7 for more details.

GUID-20240108-SS0I-DHRH-R0XJ-N9LXLSC7BV3J-low.svgFigure 2-6 Onboard Voltage Reference