SNAS783C June   2020  – February 2021 LMX2820

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 Feature Description
      1. 7.3.1  Reference Oscillator Input
      2. 7.3.2  Input Path
        1. 7.3.2.1 Input Path Doubler (OSC_2X)
        2. 7.3.2.2 Pre-R Divider (PLL_R_PRE)
        3. 7.3.2.3 Programmable Input Multiplier (MULT)
        4. 7.3.2.4 R Divider (PLL_R)
      3. 7.3.3  PLL Phase Detector and Charge Pump
      4. 7.3.4  N Divider and Fractional Circuitry
        1. 7.3.4.1 Integer N Divide Portion (PLL_N)
        2. 7.3.4.2 Fractional N Divide Portion (PLL_NUM and PLL_DEN)
        3. 7.3.4.3 Modulator Order (MASH_ORDER)
      5. 7.3.5  LD Pin Lock Detect
      6. 7.3.6  MUXOUT Pin and Readback
      7. 7.3.7  Internal VCO
        1. 7.3.7.1 VCO Calibration
          1. 7.3.7.1.1 Determining the VCO Gain and Ranges
      8. 7.3.8  Channel Divider
      9. 7.3.9  Output Frequency Doubler
      10. 7.3.10 Output Buffer
      11. 7.3.11 Power-Down Modes
      12. 7.3.12 Phase Synchronization for Multiple Devices
        1. 7.3.12.1 SYNC Categories
        2. 7.3.12.2 Phase Adjust
          1. 7.3.12.2.1 Using MASH_SEED to Create a Phase Shift
          2. 7.3.12.2.2 Static vs. Dynamic Phase Adjust
          3. 7.3.12.2.3 Fine Adjustments to Phase Adjust
      13. 7.3.13 SYSREF
      14. 7.3.14 Fast VCO Calibration
      15. 7.3.15 Double Buffering (Shadow Registers)
      16. 7.3.16 Output Mute Pin and Ping Pong Approaches
    4. 7.4 Device Functional Modes
      1. 7.4.1 External VCO Mode
      2. 7.4.2 External Feedback Input Pins
        1. 7.4.2.1 PFDIN External Feedback Mode
        2. 7.4.2.2 RFIN External Feedback Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Treatment of Unused Pins
      2. 8.1.2 External Loop Filter
      3. 8.1.3 Using Instant Calibration
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Initialization and Power-on Sequencing
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.14 Fast VCO Calibration

The time that it takes the VCO to calibrate can be reduced. Table 7-7 shows the general methods of VCO Calibration.

Table 7-7 Types of VCO Calibration
CALIBRATION TYPEDESCRIPTION
No AssistUser does nothing to improve VCO calibration speed, but the user-specified VCO_SEL, VCO_DACISET and VCO_CAPCTRL values do affect the starting point of VCO calibration.
Partial AssistUpon every frequency change, before the FCAL_EN bit is checked, the user provides the initial starting point for the VCO core (VCO_SEL), band (VCO_CAPCTRL), and amplitude (VCO_DACISET) based on values specified in the datasheet.
Full AssistThe user forces the VCO core (VCO_SEL), amplitude settings (VCO_DACISET), and frequency band (VCO_CAPCTRL) and manually sets the value. If the two frequency points are no more than 5 MHz apart and on the same VCO core, the user can set the VCO amplitude and capcode for any frequency between those two points using linear interpolation.
Instant CalibrationThe user initializes the device to generate a instant calibration. For as long as power is applied to the device, the instant calibration can be used to make ultra-fast VCO Calibration