SNAU293 May   2024 LMX1860-SEP

 

  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 Setup
      1. 2.1.1  Evaluation Setup Requirement
      2. 2.1.2  Connection Diagram
      3. 2.1.3  How to Enable Full SPI Control
      4. 2.1.4  Power Requirements
      5. 2.1.5  Pin Mode Strapping
      6. 2.1.6  Reference Clock
      7. 2.1.7  Output Connections
      8. 2.1.8  Header Information
      9. 2.1.9  Default Configuration
      10. 2.1.10 How to Generate SYSREF
      11. 2.1.11 Multiplier Mode Example
      12. 2.1.12 Divider Mode Example
      13. 2.1.13 Hybrid Mode: SPI and Pin Mode
  8. 3Software
    1. 3.1 Software Installation
    2. 3.2 Software Description
    3. 3.3 USB2ANY Interface
  9. 4Implementation Results
    1. 4.1 Buffer, Divider, and Multiplier Modes
    2. 4.2 SYSREF Generation
    3. 4.3 SYSREF Delay Generators
  10. 5Hardware Design Files
    1. 5.1 Schematic
    2. 5.2 PCB Layout
    3. 5.3 PCB Layer Stack-Up
    4. 5.4 Bill of Materials
  11. 6Additional Information
    1. 6.1 Troubleshooting Guide
      1. 6.1.1 General Guidance
      2. 6.1.2 If Output Is Not Seen on CLKOUT
      3. 6.1.3 If Device Features Are Not Active
      4. 6.1.4 If Multiplier Frequency Is Not Accurate
      5. 6.1.5 If Divider Frequency Is Not Accurate
      6. 6.1.6 If SYSREF Is Not Observed
    2. 6.2 Trademarks

4.3 SYSREF Delay Generators

In generator modes, the SYSREF can be delayed by picosecond-size steps to more closely meet setup and hold requirements for high-frequency clock outputs. A delay divider, SYSREF_DELAY_DIV, generates the interpolator frequency fINTERPOLATOR, which is usually in the range of 400MHz to 800MHz. This interpolator frequency is further subdivided into 512 delay codes, allowing approximately 2.5ps to 5ps delay steps across most of the CLKIN frequency range.

Each channel has delay codes, which can be entered. The delay code algorithm is documented in the data sheet. To simplify delay calculation, the GUI provides an estimated relative delay: enter the relative delay, and the GUI calculates the correct step values to achieve the requested delay as closely as possible. Alternately, the register-based delay fields can be stepped through or programmed to achieve the same result.

LMX1860SEPEVM SYSREF Delay in 5-Code Steps Figure 4-6 SYSREF Delay in 5-Code Steps