SBAU435 February   2024

 

  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

2.8 Clock Tree

Figure 3-8 shows the different clock options for the ADS127L18EVM that are selected by jumper JP1. The default setting for JP1 is the 2-3 position (EVM CLK), which enables the local 32.768MHz oscillator (Y1) on the ADS127L18EVM board. This clock is routed to the clock input of the ADS127L18 to support all speed modes. Moving JP1 to the 1-2 position (EXT CLK) allows an external clock supplied on the SMA connector (J2). Use a CMOS square-wave signal with an amplitude equal to 1.8V (IOVDD) and a frequency within the specified range of the ADS127L18.

CAUTION: The maximum operating voltage level for the clock input (J2) is 1.95V. Exceeding this voltage level or applying a clock input before the ADS127L18EVM has been powered-up can cause permanent damage to the ADS127L18.
GUID-20240104-SS0I-J6QF-5MW7-QRCCJV3JNSNZ-low.svgFigure 2-8 Clock Tree