SNAS680E December   2015  – August 2022 LMX2582

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Functional Description
      1. 7.3.1  Input Signal
      2. 7.3.2  Input Signal Path
      3. 7.3.3  PLL Phase Detector and Charge Pump
      4. 7.3.4  N Divider and Fractional Circuitry
      5. 7.3.5  Voltage Controlled Oscillator
      6. 7.3.6  VCO Calibration
      7. 7.3.7  Channel Divider
      8. 7.3.8  Output Distribution
      9. 7.3.9  Output Buffer
      10. 7.3.10 Phase Adjust
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power Down
      2. 7.4.2 Lock Detect
      3. 7.4.3 Register Readback
    5. 7.5 Programming
      1. 7.5.1 Recommended Initial Power on Programming Sequence
      2. 7.5.2 Recommended Sequence for Changing Frequencies
    6. 7.6 Register Maps
      1. 7.6.1 LMX2582 Register Map – Default Values
        1. 7.6.1.1 Register Descriptions
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Optimization of Spurs
        1. 8.1.1.1 Understanding Spurs by Offsets
        2. 8.1.1.2 Spur Mitigation Techniques
      2. 8.1.2  Configuring the Input Signal Path
        1. 8.1.2.1 Input Signal Noise Scaling
      3. 8.1.3  Input Pin Configuration
      4. 8.1.4  Using the OSCin Doubler
      5. 8.1.5  Using the Input Signal Path Components
        1. 8.1.5.1 Moving Phase Detector Frequency
        2. 8.1.5.2 Multiplying and Dividing by the Same Value
      6. 8.1.6  Designing for Output Power
      7. 8.1.7  Current Consumption Management
      8. 8.1.8  Decreasing Lock Time
      9. 8.1.9  Modeling and Understanding PLL FOM and Flicker Noise
      10. 8.1.10 External Loop Filter
    2. 8.2 Typical Application
      1. 8.2.1 Design for Low Jitter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

7.3.7 Channel Divider

GUID-109C492C-14B0-429D-9537-B65020784F37-low.gifFigure 7-2 Channel Divider Diagram

To go below the VCO lower bound, the channel divider must be used. The channel divider consists of three programmable dividers controlled by the registers CHDIV_SEG1, CHDIV_SEG2, CHDIV_SEG3. The Multiplexer (programmed with register CHDIV_SEG_SEL) selects which divider is included in the path. The minimum division is 2 while the maximum division is 192. Un-used dividers can be powered down to save current consumption. The entire channel divider can be powered down with register CHDIV_EN = 0 or selectively setting registers CHDIV_SEG1_EN = 0, CHDIV_SEG2_EN = 0 ,CHDIV_SEG3_EN = 0. Unused buffers may also be powered down with registers CHDIV_DISTA_EN and CHDIV_DIST_EN. There are restrictions on the maximum VCO frequency when channel divider is engaged.

Table 7-4 Channel Divider vs VCO Frequency
OUTPUT FREQUENCY (MHz) CHDIV SEGMENT TOTAL DIVISION VCO FREQUENCY (MHz)
MIN MAX SEG1 SEG2 SEG3 MIN MAX
1775 3550 2 1 1 2 3550 7100
1184 2200 3 1 1 3 3552 6600
888 1184 2 2 1 4 3552 4736
592 888 3 2 1 6 3552 5328
444 592 2 4 1 8 3552 4736
296 444 2 6 1 12 3552 5328
222 296 2 8 1 16 3552 4736
148 222 3 8 1 24 3552 5328
111 148 2 8 2 32 3552 4736
99 111 3 6 2 36 3564 3996
74 99 3 8 2 48 3552 4752
56 74 2 8 4 64 3584 4736
37 56 2 8 6 96 3552 5376
28 37 2 8 8 128 3584 4736
20 28 3 8 8 192 3840 5376