SNAU309 October   2025

 

  1.   1
  2.   Description
  3.   Features
  4.   Applications
  5.   5
  6. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  7. 2Hardware
    1. 2.1 EVM Quick Start
      1. 2.1.1 Hardware Setup
      2. 2.1.2 Software Setup
    2. 2.2 EVM Configuration
      1. 2.2.1 Device Operational Modes
      2. 2.2.2 Power Supply
      3. 2.2.3 Logic Inputs and Outputs
      4. 2.2.4 Configuring the Clock Outputs
      5. 2.2.5 Using the USB Interface Connection
  8. 3Software
    1. 3.1 Software Installation
    2. 3.2 Software Description
      1. 3.2.1 User Controls Page
      2. 3.2.2 Raw Registers Page
      3. 3.2.3 Global Settings Page
      4. 3.2.4 EFUSE Pages Page
      5. 3.2.5 GPIO Page
      6. 3.2.6 FODs Page
      7. 3.2.7 Inputs Page
      8. 3.2.8 OUT0 Page
      9. 3.2.9 OUT1 & OUT2 Page
  9. 4Implementation Results
    1. 4.1 Evaluation Setup
    2. 4.2 Performance Data and Results
  10. 5Hardware Design Files
    1. 5.1 Schematics
    2. 5.2 PCB Layouts
    3. 5.3 Bill of Materials (BOM)
  11. 6Additional Information
    1. 6.1 Trademarks
  12. 7Related Documentation
    1. 7.1 Supplemental Content

2.2.1 Device Operational Modes

The LMK3H2108 can be configured to start up on one of four OTP pages when any combination of GPIO_0, GPIO_1, and GPIO_2 are configured as OTP Page Selection (OTP_SEL) pins on each page. If no GPIO are configured as OTP_SEL pins, the device loads the default OTP page selected in the configuration, most commonly OTP Page 0. On each OTP page, the I2C interface is available.

The default configuration when using an LMK3H2108A00 device is eight 100MHz 100Ω LP-HCSL outputs. OTP Page 0 has no spread spectrum clocking (SSC) enabled, and each other OTP page uses spread spectrum:

  • Page 0: No SSC
  • Page 1: -0.1% downspread SSC
  • Page 2: -0.3% down-spread SSC
  • Page 3: -0.5% down-spread SSC

An LMK6H device is present on the board for optionally driving IN0 from a PCIe-compatible reference in buffer mode..