SNAS674B September   2015  – February 2017 LMK61E2

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 - Power Supply
    6. 6.6  LVPECL Output Characteristics
    7. 6.7  LVDS Output Characteristics
    8. 6.8  HCSL Output Characteristics
    9. 6.9  OE Input Characteristics
    10. 6.10 ADD Input Characteristics
    11. 6.11 Frequency Tolerance Characteristics
    12. 6.12 Power-On/Reset Characteristics (VDD)
    13. 6.13 I2C-Compatible Interface Characteristics (SDA, SCL)
    14. 6.14 PSRR Characteristics
    15. 6.15 Other Characteristics
    16. 6.16 PLL Clock Output Jitter Characteristics
    17. 6.17 Typical 156.25-MHz Output Phase Noise Characteristics
    18. 6.18 Typical 161.1328125 MHz Output Phase Noise Characteristics
    19. 6.19 Additional Reliability and Qualification
    20. 6.20 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Device Output Configurations
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Device Block-Level Description
      2. 8.3.2  Device Configuration Control
      3. 8.3.3  Register File Reference Convention
      4. 8.3.4  Configuring the PLL
      5. 8.3.5  Integrated Oscillator
      6. 8.3.6  Reference Doubler
      7. 8.3.7  Phase Frequency Detector
      8. 8.3.8  Feedback Divider (N)
      9. 8.3.9  Fractional Circuitry
      10. 8.3.10 Charge Pump
      11. 8.3.11 Loop Filter
      12. 8.3.12 VCO Calibration
      13. 8.3.13 High-Speed Output Divider
      14. 8.3.14 High-Speed Clock Output
      15. 8.3.15 Device Status
        1. 8.3.15.1 Loss of Lock
    4. 8.4 Device Functional Modes
      1. 8.4.1 Interface and Control
    5. 8.5 Programming
      1. 8.5.1 I2C Serial Interface
      2. 8.5.2 Block Register Write
      3. 8.5.3 Block Register Read
      4. 8.5.4 Write SRAM
      5. 8.5.5 Write EEPROM
      6. 8.5.6 Read SRAM
      7. 8.5.7 Read EEPROM
    6. 8.6 EEPROM Map
    7. 8.7 Register Map
      1. 8.7.1 Register Descriptions
        1. 8.7.1.1  VNDRID_BY1 Register; R0
        2. 8.7.1.2  VNDRID_BY0 Register; R1
        3. 8.7.1.3  PRODID Register; R2
        4. 8.7.1.4  REVID Register; R3
        5. 8.7.1.5  SLAVEADR Register; R8
        6. 8.7.1.6  EEREV Register; R9
        7. 8.7.1.7  DEV_CTL Register; R10
        8. 8.7.1.8  XO_CAPCTRL_BY1 Register; R16
        9. 8.7.1.9  XO_CAPCTRL_BY0 Register; R17
        10. 8.7.1.10 DIFFCTL Register; R21
        11. 8.7.1.11 OUTDIV_BY1 Register; R22
        12. 8.7.1.12 OUTDIV_BY0 Register; R23
        13. 8.7.1.13 PLL_NDIV_BY1 Register; R25
        14. 8.7.1.14 PLL_NDIV_BY0 Register; R26
        15. 8.7.1.15 PLL_FRACNUM_BY2 Register; R27
        16. 8.7.1.16 PLL_FRACNUM_BY1 Register; R28
        17. 8.7.1.17 PLL_FRACNUM_BY0 Register; R29
        18. 8.7.1.18 PLL_FRACDEN_BY2 Register; R30
        19. 8.7.1.19 PLL_FRACDEN_BY1 Register; R31
        20. 8.7.1.20 PLL_FRACDEN_BY0 Register; R32
        21. 8.7.1.21 PLL_MASHCTRL Register; R33
        22. 8.7.1.22 PLL_CTRL0 Register; R34
        23. 8.7.1.23 PLL_CTRL1 Register; R35
        24. 8.7.1.24 PLL_LF_R2 Register; R36
        25. 8.7.1.25 PLL_LF_C1 Register; R37
        26. 8.7.1.26 PLL_LF_R3 Register; R38
        27. 8.7.1.27 PLL_LF_C3 Register; R39
        28. 8.7.1.28 PLL_CALCTRL Register; R42
        29. 8.7.1.29 NVMSCRC Register; R47
        30. 8.7.1.30 NVMCNT Register; R48
        31. 8.7.1.31 NVMCTL Register; R49
        32. 8.7.1.32 MEMADR Register; R51
        33. 8.7.1.33 NVMDAT Register; R52
        34. 8.7.1.34 RAMDAT Register; R53
        35. 8.7.1.35 NVMUNLK Register; R56
        36. 8.7.1.36 INT_LIVE Register; R66
        37. 8.7.1.37 SWRST Register; R72
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Jitter Considerations in Serdes Systems
      2. 9.2.2 Frequency Margining
        1. 9.2.2.1 Fine Frequency Margining
        2. 9.2.2.2 Coarse Frequency Margining
      3. 9.2.3 Design Requirements
        1. 9.2.3.1 Detailed Design Procedure
          1. 9.2.3.1.1 Custom Design With WEBENCH® Tools
          2. 9.2.3.1.2 Device Selection
          3. 9.2.3.1.3 VCO Frequency Calculation
          4. 9.2.3.1.4 Device Configuration
          5. 9.2.3.1.5 PLL Loop Filter Design
          6. 9.2.3.1.6 Spur Mitigation Techniques
            1. 9.2.3.1.6.1 Phase Detection Spur
            2. 9.2.3.1.6.2 Integer Boundary Fractional Spur
            3. 9.2.3.1.6.3 Primary Fractional Spur
            4. 9.2.3.1.6.4 Sub-Fractional Spur
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Ensured Thermal Reliability
      2. 11.1.2 Best Practices for Signal Integrity
      3. 11.1.3 Recommended Solder Reflow Profile
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

11 Layout

11.1 Layout Guidelines

Ensured Thermal Reliability, Best Practices for Signal Integrity and Recommended Solder Reflow Profile provide recommendations for board layout, solder reflow profile and power supply bypassing when using LMK61E2 to ensure good thermal / electrical performance and overall signal integrity of entire system.

11.1.1 Ensured Thermal Reliability

The LMK61E2 is a high performance device. Therefore careful attention must be paid to device configuration and printed circuit board (PCB) layout with respect to power consumption. The ground pin needs to be connected to the ground plane of the PCB through three vias or more, as shown in Figure 34, to maximize thermal dissipation out of the package.

Equation 3 describes the relationship between the PCB temperature around the LMK61E2 and its junction temperature.

Equation 3. TB = TJ – ΨJB * P

where

  • TB: PCB temperature around the LMK61E2
  • TJ: Junction temperature of LMK61E2
  • ΨJB: Junction-to-board thermal resistance parameter of LMK61E2 (36.7°C/W without airflow)
  • P: On-chip power dissipation of LMK61E2

In order to ensure that the maximum junction temperature of LMK61E2 is below 125°C, it can be calculated that the maximum PCB temperature without airflow should be at 100°C or below when the device is optimized for best performance resulting in maximum on-chip power dissipation of 0.68 W.

11.1.2 Best Practices for Signal Integrity

For best electrical performance and signal integrity of entire system with LMK61E2, it is recommended to route vias into decoupling capacitors and then into the LMK61E2. It is also recommended to increase the via count and width of the traces wherever possible. These steps ensure lowest impedance and shortest path for high frequency current flow. Figure 34 shows the layout recommendation for LMK61E2.

11.1.3 Recommended Solder Reflow Profile

It is recommended to follow the solder paste supplier's recommendations to optimize flux activity and to achieve proper melting temperatures of the alloy within the guidelines of J-STD-20. It is preferable for the LMK61E2 to be processed with the lowest peak temperature possible while also remaining below the components peak temperature rating as listed on the MSL label. The exact temperature profile would depend on several factors including maximum peak temperature for the component as rated on the MSL label, Board thickness, PCB material type, PCB geometries, component locations, sizes, densities within PCB, as well solder manufactures recommended profile, and capability of the reflow equipment to as confirmed by the SMT assembly operation.

11.2 Layout Example

LMK61E2 layout_example_snas674.png Figure 34. LMK61E2 Layout Recommendation for Power Supply and Ground