SNAU294 May   2024 LMX1205

 

  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 Jumper Information
    2. 2.2 Setup
      1. 2.2.1 Evaluation Setup Requirement
      2. 2.2.2 Connection Diagram
    3. 2.3 Power Requirements
    4. 2.4 Reference Clock
    5. 2.5 Output Connections
    6. 2.6 Test Points
  8. 3Software
    1. 3.1 Software Description
    2. 3.2 Software Installation
    3. 3.3 USB2ANY Interface
  9. 4Implementation Results
    1. 4.1 Buffer Mode
    2. 4.2 Divider Mode
    3. 4.3 Multiplier Mode
    4. 4.4 SYSREF Generation
  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

4.4 SYSREF Generation

To generate a continuous SYSREF clock signal, proceed with the following steps:

  1. Set SYSREFREQ_MODE = SYSREF
  2. Set SYSREF_MODE = Continuous
  3. Set SYSREF_EN = HIGH
  4. Provide a logic HIGH to SYSREFREQ pins. For example, SYSINP = 1.4V; SYSINN = 1.0V
LMX1205EVM SYSREF Continuous Mode Configuration Figure 4-7 SYSREF Continuous Mode Configuration
LMX1205EVM SYSREF Continuous Clock Generation (AC-coupled to a scope) Figure 4-8 SYSREF Continuous Clock Generation (AC-coupled to a scope)

To generate SYSREF pulses:

  1. Change SYSREF_MODE = Pulser and set SYSREF_PULSE_CNT to the desired value.
  2. Provide a LOW to HIGH transition to SYSREFREQ pins.
LMX1205EVM SYSREF Pulser Mode Configuration Figure 4-9 SYSREF Pulser Mode Configuration
LMX1205EVM SYSREF Pulser Clock Output (DC-coupled to a scope) Figure 4-10 SYSREF Pulser Clock Output (DC-coupled to a scope)

To put the device in SYSREF repeater mode:

  1. Change SYSREF_MODE = Repeater
  2. Provide a SYSREF clock or pulses to SYSREFREQ.
LMX1205EVM SYSREF Repeater Mode Configuration Figure 4-11 SYSREF Repeater Mode Configuration