SNAS522K September   2011  – December 2023 LMK03806

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Differential Voltage Measurement Terminology
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Features Description
      1. 7.3.1 Serial MICROWIRE Timing Diagram and Terminology
      2. 7.3.2 Crystal Support With Buffered Outputs
      3. 7.3.3 Integrated Loop Filter Poles
      4. 7.3.4 Integrated VCO
      5. 7.3.5 Clock Distribution
        1. 7.3.5.1 CLKout DIvider
        2. 7.3.5.2 Programmable Output Type
        3. 7.3.5.3 Clock Output Synchronization
      6. 7.3.6 Default Start-Up Clocks
    4. 7.4 Device Functional Modes
    5. 7.5 Programming
      1. 7.5.1 General Information
        1. 7.5.1.1 Special Programming Case for R0 to R5 for CLKoutX_Y_DIV > 25
        2. 7.5.1.2 Recommended Initial Programming Sequence
        3. 7.5.1.3 READBACK
          1. 7.5.1.3.1 Readback Example
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Crystal Interface
      2. 8.1.2 Driving OSCin Pins With a Single-Ended Source
      3. 8.1.3 Driving OSCin Pins With a Differential Source
      4. 8.1.4 Frequency Planning With the LMK03806
      5. 8.1.5 Configuring the PLL
        1. 8.1.5.1 Example PLL Configuration
      6. 8.1.6 Digital Lock Detect
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Device Selection
          1. 8.2.2.1.1 Clock Architect
          2. 8.2.2.1.2 Clock Design Tool
          3. 8.2.2.1.3 Calculation Using LCM
        2. 8.2.2.2 Device Configuration
        3. 8.2.2.3 PLL Loop Filter Design
          1. 8.2.2.3.1 Example Loop Filter Design
        4. 8.2.2.4 Other Device Specific Configuration
          1. 8.2.2.4.1 Digital Lock Detect
        5. 8.2.2.5 Device Programming
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
      1. 8.3.1 System Level Diagram
    4. 8.4 Best Design Practices
      1. 8.4.1 LVCMOS Complementary vs. Non-Complementary Operation
      2. 8.4.2 LVPECL Outputs
      3. 8.4.3 Sharing MICROWIRE (SPI) Lines
      4. 8.4.4 SYNC Pin
      5. 8.4.5 CLKout Vcc Pins
    5. 8.5 Power Supply Recommendations
      1. 8.5.1 Current Consumption and Power Dissipation Calculations
    6. 8.6 Layout
      1. 8.6.1 Layout Guidelines
      2. 8.6.2 Layout Example
  10. 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
  11. 10Register Maps
    1. 10.1  Default Device Register Settings After Power On Reset
    2. 10.2  Register R0 TO R5
      1. 10.2.1 CLKoutX_Y_PD, Powerdown CLKoutX_Y Output Path
      2. 10.2.2 RESET
      3. 10.2.3 POWERDOWN
      4. 10.2.4 CLKoutX_Y_DIV, Clock Output Divide
    3. 10.3  Registers R6 TO R8
      1. 10.3.1 CLKoutX_TYPE
    4. 10.4  REGISTER R9
    5. 10.5  REGISTER R10
      1. 10.5.1 OSCout1_TYPE, LVPECL Output Amplitude Control
      2. 10.5.2 OSCout0_TYPE
      3. 10.5.3 EN_OSCoutX, OSCout Output Enable
      4. 10.5.4 OSCoutX_MUX, Clock Output Mux
      5. 10.5.5 OSCout_DIV, Oscillator Output Divide
    6. 10.6  REGISTER R11
      1. 10.6.1 NO_SYNC_CLKoutX_Y
      2. 10.6.2 SYNC_POL_INV
      3. 10.6.3 SYNC_TYPE
      4. 10.6.4 EN_PLL_XTAL
    7. 10.7  REGISTER R12
      1. 10.7.1 LD_MUX
      2. 10.7.2 LD_TYPE
      3. 10.7.3 SYNC_PLL_DLD
    8. 10.8  REGISTER R13
      1. 10.8.1 READBACK_TYPE
      2. 10.8.2 GPout0
    9. 10.9  REGISTER 14
      1. 10.9.1 GPout1
    10. 10.10 REGISTER 16
    11. 10.11 REGISTER 24
      1. 10.11.1 PLL_C4_LF, PLL Integrated Loop Filter Component
      2. 10.11.2 PLL_C3_LF, PLL Integrated Loop Filter Component
      3. 10.11.3 PLL_R4_LF, PLL Integrated Loop Filter Component
      4. 10.11.4 PLL_R3_LF, PLL Integrated Loop Filter Component
    12. 10.12 REGISTER 26
      1. 10.12.1 EN_PLL_REF_2X, PLL Reference Frequency Doubler
      2. 10.12.2 PLL_CP_GAIN, PLL Charge Pump Current
      3. 10.12.3 PLL_DLD_CNT
    13. 10.13 REGISTER 28
      1. 10.13.1 PLL_R, PLL R Divider
    14. 10.14 REGISTER 29
      1. 10.14.1 OSCin_FREQ, PLL Oscillator Input Frequency Register
      2. 10.14.2 PLL_N_CAL, PLL N Calibration Divider
    15. 10.15 REGISTER 30
      1. 10.15.1 PLL_P, PLL N Prescaler Divider
      2. 10.15.2 PLL_N, PLL N Divider
    16. 10.16 REGISTER 31
      1. 10.16.1 READBACK_ADDR
      2. 10.16.2 uWire_LOCK
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2.2 Device Configuration

The tools listed above automatically configure the clock solution to meet the input and output frequency requirements given and make assumptions about certain parameters to give default simulation results. The assumptions made are to maximize input frequencies, Fpd, and charge pump currents while minimizing Fvco and divider values. We will also outline the steps for manually configuring the device below for greater flexibility. Note that this procedure is the same as the one outlined in the Frequency Planning With the LMK03806 and Configuring the PLL sections, which can be referenced for a more detailed explanation.

We are given the target output frequencies of 156.25 MHz, 125 MHz, 100 MHz, and 25 MHz with an FOSCin of 20 MHz. As previously calculated, the LCM and Fvco is 2500 MHz.

First, we will consider the PLL reference path. For lowest possible in-band PLL flat noise, we will try to maximize Fpd. 20 MHz is the highest frequency which divides into 2500 MHz by an integer value and which can also be synthesized from FOSCin. As noted earlier, when FOSCin and fpd are equal, the best PLL in-band noise can be achieved with the PLL reference doubler enabled (EN_PLL_REF_2X=1) and the PLL reference divider is 2 (PLL_R =2).

Next, we will consider the PLL feedback path. As determined earlier, Fvco is 2500 MHz and the Fpd is 20 MHz, which is 2500 MHz divided by 125. The prescaler and N divider settings together must divide Fvco by 125. The only setting that works in this case is a prescaler value of 5 and an N divider value of 25.

At this point the design meets all input and output frequency requirements and it is possible to design a loop filter for the application and simulate phase noise of the output clocks.