SNAU246A June   2020  – January 2021 LMX2820

 

  1. 1Trademarks
  2. 2LMX2820EVM Evaluation Module
    1. 2.1 Evaluation Module Contents
    2. 2.2 Evaluation Setup Requirement
    3. 2.3 Resources
  3. 3Setup
    1. 3.1 Connection Diagram
    2. 3.2 Power Supply
    3. 3.3 Reference Clock
    4. 3.4 RF Output
    5. 3.5 Programming
    6. 3.6 Evaluation Software
  4. 4Typical Measurement
    1. 4.1 Default Configuration
      1. 4.1.1 Loop Filter
      2. 4.1.2 Typical Output
    2. 4.2 Additional Tests
      1. 4.2.1 SYSREF Example
      2. 4.2.2 Offset Mixing With PFDIN Pin
      3. 4.2.3 External VCO Mode
      4. 4.2.4 Register Readback
  5. 5Schematic
  6. 6PCB Layout and Layer Stack-Up
    1. 6.1 PCB Layer Stack-Up
    2. 6.2 PCB Layout
  7. 7Bill of Materials
  8. 8Troubleshooting Guide
    1.     A Using Different Reference Clock
      1.      B USB2ANY Firmware Upgrade
        1.       C Revision History

4.2.1 SYSREF Example

The SROUT of LMX2820 can be used to generate or duplicate SYSREF signal. The output of SROUT can be a single pulse, series of pulse, or a continuous stream of pulses. These pulses are synchronous with the RFOUT signal with an adjustable delay. To use the SYSREF capability, the PLL must be in phase SYNC mode with PHASE_SYNC_EN = 1. Here is an example of Pulsed mode.

GUID-6E505DB3-E742-4D4E-AEA5-3152FCACDE2B-low.png Figure 4-3 SYSREF Pulsed Mode Setting