SNAS785D November   2019  – March 2022 LMX2694-EP

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 Timing Diagrams
    8. 6.8 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  Reference Path
        1. 7.3.2.1 OSCIN Doubler (OSC_2X)
        2. 7.3.2.2 Pre-R Divider (PLL_R_PRE)
        3. 7.3.2.3 Post-R Divider (PLL_R)
      3. 7.3.3  State Machine Clock
      4. 7.3.4  PLL Phase Detector and Charge Pump
      5. 7.3.5  N Divider and Fractional Circuitry
      6. 7.3.6  MUXOUT Pin
        1. 7.3.6.1 Serial Data Output for Readback
        2. 7.3.6.2 Lock Detect Indicator Set as Type “VCOCal”
        3. 7.3.6.3 Lock Detect Indicator Set as Type “Vtune and VCOCal”
      7. 7.3.7  VCO (Voltage-Controlled Oscillator)
        1. 7.3.7.1 VCO Calibration
        2. 7.3.7.2 Determining the VCO Gain
      8. 7.3.8  Channel Divider
      9. 7.3.9  Output Buffer
      10. 7.3.10 Powerdown Modes
      11. 7.3.11 Treatment of Unused Pins
      12. 7.3.12 Phase Synchronization
        1. 7.3.12.1 General Concept
        2. 7.3.12.2 Categories of Applications for SYNC
        3. 7.3.12.3 Procedure for Using SYNC
        4. 7.3.12.4 SYNC Input Pin
      13. 7.3.13 Phase Adjust
      14. 7.3.14 Fine Adjustments for Phase Adjust and Phase SYNC
      15. 7.3.15 SYSREF
        1. 7.3.15.1 Programmable Fields
        2. 7.3.15.2 Input and Output Pin Formats
          1. 7.3.15.2.1 SYSREF Output Format
        3. 7.3.15.3 SYSREF Examples
        4. 7.3.15.4 SYSREF Procedure
    4. 7.4 Device Functional Modes
    5. 7.5 Programming
      1. 7.5.1 Recommended Initial Power-Up Sequence
      2. 7.5.2 Recommended Sequence for Changing Frequencies
    6. 7.6 Register Maps
      1. 7.6.1   R0 Register (Offset = 0x0) [reset = 0x200C]
      2. 7.6.2   R1 Register (Offset = 0x1) [reset = 0x80C]
      3. 7.6.3   R2 Register (Offset = 0x2) [reset = 0x500]
      4. 7.6.4   R3 Register (Offset = 0x3) [reset = 0x642]
      5. 7.6.5   R4 Register (Offset = 0x4) [reset = 0xA43]
      6. 7.6.6   R5 Register (Offset = 0x5) [reset = 0xC8]
      7. 7.6.7   R6 Register (Offset = 0x6) [reset = 0xC802]
      8. 7.6.8   R7 Register (Offset = 0x7) [reset = 0xB2]
      9. 7.6.9   R8 Register (Offset = 0x8) [reset = 0x2000]
      10. 7.6.10  R9 Register (Offset = 0x9) [reset = 0x604]
      11. 7.6.11  R10 Register (Offset = 0xA) [reset = 0x10F8]
      12. 7.6.12  R11 Register (Offset = 0xB) [reset = 0x18]
      13. 7.6.13  R12 Register (Offset = 0xC) [reset = 0x5001]
      14. 7.6.14  R13 Register (Offset = 0xD) [reset = 0x4000]
      15. 7.6.15  R14 Register (Offset = 0xE) [reset = 0x1E70]
      16. 7.6.16  R15 Register (Offset = 0xF) [reset = 0x64F]
      17. 7.6.17  R16 Register (Offset = 0x10) [reset = 0x80]
      18. 7.6.18  R17 Register (Offset = 0x11) [reset = 0x96]
      19. 7.6.19  R18 Register (Offset = 0x12) [reset = 0x64]
      20. 7.6.20  R19 Register (Offset = 0x13) [reset = 0x27B7]
      21. 7.6.21  R20 Register (Offset = 0x14) [reset = 0x3048]
      22. 7.6.22  R21 Register (Offset = 0x15) [reset = 0x401]
      23. 7.6.23  R22 Register (Offset = 0x16) [reset = 0x1]
      24. 7.6.24  R23 Register (Offset = 0x17) [reset = 0x7C]
      25. 7.6.25  R24 Register (Offset = 0x18) [reset = 0x71A]
      26. 7.6.26  R25 Register (Offset = 0x19) [reset = 0x624]
      27. 7.6.27  R26 Register (Offset = 0x1A) [reset = 0xDB0]
      28. 7.6.28  R27 Register (Offset = 0x1B) [reset = 0x2]
      29. 7.6.29  R28 Register (Offset = 0x1C) [reset = 0x488]
      30. 7.6.30  R29 Register (Offset = 0x1D) [reset = 0x318C]
      31. 7.6.31  R30 Register (Offset = 0x1E) [reset = 0x318C]
      32. 7.6.32  R31 Register (Offset = 0x1F) [reset = 0xC3EC]
      33. 7.6.33  R32 Register (Offset = 0x20) [reset = 0x393]
      34. 7.6.34  R33 Register (Offset = 0x21) [reset = 0x1E21]
      35. 7.6.35  R34 Register (Offset = 0x22) [reset = 0x10]
      36. 7.6.36  R35 Register (Offset = 0x23) [reset = 0x4]
      37. 7.6.37  R36 Register (Offset = 0x24) [reset = 0x70]
      38. 7.6.38  R37 Register (Offset = 0x25) [reset = 0x205]
      39. 7.6.39  R38 Register (Offset = 0x26) [reset = 0xFFFF]
      40. 7.6.40  R39 Register (Offset = 0x27) [reset = 0xFFFF]
      41. 7.6.41  R40 Register (Offset = 0x28) [reset = 0x0]
      42. 7.6.42  R41 Register (Offset = 0x29) [reset = 0x0]
      43. 7.6.43  R42 Register (Offset = 0x2A) [reset = 0x0]
      44. 7.6.44  R43 Register (Offset = 0x2B) [reset = 0x0]
      45. 7.6.45  R44 Register (Offset = 0x2C) [reset = 0x22A2]
      46. 7.6.46  R45 Register (Offset = 0x2D) [reset = 0xC622]
      47. 7.6.47  R46 Register (Offset = 0x2E) [reset = 0x7F0]
      48. 7.6.48  R47 Register (Offset = 0x2F) [reset = 0x300]
      49. 7.6.49  R48 Register (Offset = 0x30) [reset = 0x3E0]
      50. 7.6.50  R49 Register (Offset = 0x31) [reset = 0x4180]
      51. 7.6.51  R50 Register (Offset = 0x32) [reset = 0x80]
      52. 7.6.52  R51 Register (Offset = 0x33) [reset = 0x80]
      53. 7.6.53  R52 Register (Offset = 0x34) [reset = 0x420]
      54. 7.6.54  R53 Register (Offset = 0x35) [reset = 0x0]
      55. 7.6.55  R54 Register (Offset = 0x36) [reset = 0x0]
      56. 7.6.56  R55 Register (Offset = 0x37) [reset = 0x0]
      57. 7.6.57  R56 Register (Offset = 0x38) [reset = 0x0]
      58. 7.6.58  R57 Register (Offset = 0x39) [reset = 0x0]
      59. 7.6.59  R58 Register (Offset = 0x3A) [reset = 0x8001]
      60. 7.6.60  R59 Register (Offset = 0x3B) [reset = 0x1]
      61. 7.6.61  R60 Register (Offset = 0x3C) [reset = 0x3E8]
      62. 7.6.62  R61 Register (Offset = 0x3D) [reset = 0xA8]
      63. 7.6.63  R62 Register (Offset = 0x3E) [reset = 0xAE]
      64. 7.6.64  R63 Register (Offset = 0x3F) [reset = 0x0]
      65. 7.6.65  R64 Register (Offset = 0x40) [reset = 0x1388]
      66. 7.6.66  R65 Register (Offset = 0x41) [reset = 0x0]
      67. 7.6.67  R66 Register (Offset = 0x42) [reset = 0x140]
      68. 7.6.68  R67 Register (Offset = 0x43) [reset = 0x0]
      69. 7.6.69  R68 Register (Offset = 0x44) [reset = 0x3E8]
      70. 7.6.70  R69 Register (Offset = 0x45) [reset = 0x0]
      71. 7.6.71  R70 Register (Offset = 0x46) [reset = 0xC350]
      72. 7.6.72  R71 Register (Offset = 0x47) [reset = 0x80]
      73. 7.6.73  R72 Register (Offset = 0x48) [reset = 0x1]
      74. 7.6.74  R73 Register (Offset = 0x49) [reset = 0x3F]
      75. 7.6.75  R74 Register (Offset = 0x4A) [reset = 0x0]
      76. 7.6.76  R75 Register (Offset = 0x4B) [reset = 0x800]
      77. 7.6.77  R76 Register (Offset = 0x4C) [reset = 0xC]
      78. 7.6.78  R77 Register (Offset = 0x4D) [reset = 0x0]
      79. 7.6.79  R78 Register (Offset = 0x4E) [reset = 0x64]
      80. 7.6.80  R79 Register (Offset = 0x4F) [reset = 0x0]
      81. 7.6.81  R80 Register (Offset = 0x50) [reset = 0x0]
      82. 7.6.82  R81 Register (Offset = 0x51) [reset = 0x0]
      83. 7.6.83  R82 Register (Offset = 0x52) [reset = 0x0]
      84. 7.6.84  R83 Register (Offset = 0x53) [reset = 0x0]
      85. 7.6.85  R84 Register (Offset = 0x54) [reset = 0x0]
      86. 7.6.86  R85 Register (Offset = 0x55) [reset = 0x0]
      87. 7.6.87  R86 Register (Offset = 0x56) [reset = 0x0]
      88. 7.6.88  R87 Register (Offset = 0x57) [reset = 0x0]
      89. 7.6.89  R88 Register (Offset = 0x58) [reset = 0x0]
      90. 7.6.90  R89 Register (Offset = 0x59) [reset = 0x0]
      91. 7.6.91  R90 Register (Offset = 0x5A) [reset = 0x0]
      92. 7.6.92  R91 Register (Offset = 0x5B) [reset = 0x0]
      93. 7.6.93  R92 Register (Offset = 0x5C) [reset = 0x0]
      94. 7.6.94  R93 Register (Offset = 0x5D) [reset = 0x0]
      95. 7.6.95  R94 Register (Offset = 0x5E) [reset = 0x0]
      96. 7.6.96  R95 Register (Offset = 0x5F) [reset = 0x0]
      97. 7.6.97  R96 Register (Offset = 0x60) [reset = 0x0]
      98. 7.6.98  R97 Register (Offset = 0x61) [reset = 0x0]
      99. 7.6.99  R98 Register (Offset = 0x62) [reset = 0x0]
      100. 7.6.100 R99 Register (Offset = 0x63) [reset = 0x0]
      101. 7.6.101 R100 Register (Offset = 0x64) [reset = 0x0]
      102. 7.6.102 R101 Register (Offset = 0x65) [reset = 0x0]
      103. 7.6.103 R102 Register (Offset = 0x66) [reset = 0x0]
      104. 7.6.104 R103 Register (Offset = 0x67) [reset = 0x0]
      105. 7.6.105 R104 Register (Offset = 0x68) [reset = 0x0]
      106. 7.6.106 R105 Register (Offset = 0x69) [reset = 0x440]
      107. 7.6.107 R106 Register (Offset = 0x6A) [reset = 0x7]
      108. 7.6.108 R107 Register (Offset = 0x6B) [reset = 0x0]
      109. 7.6.109 R108 Register (Offset = 0x6C) [reset = 0x0]
      110. 7.6.110 R109 Register (Offset = 0x6D) [reset = 0x0]
      111. 7.6.111 R110 Register (Offset = 0x6E) [reset = 0x0]
      112. 7.6.112 R111 Register (Offset = 0x6F) [reset = 0x0]
      113. 7.6.113 R112 Register (Offset = 0x70) [reset = 0x0]
      114. 7.6.114 R113 Register (Offset = 0x71) [reset = 0x0]
      115. 7.6.115 R114 Register (Offset = 0x72) [reset = 0x0]
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 OSCIN Configuration
      2. 8.1.2 OSCIN Slew Rate
      3. 8.1.3 RF Output Buffer Power Control
      4. 8.1.4 RF Output Buffer Pullup
        1. 8.1.4.1 Resistor Pullup
        2. 8.1.4.2 Inductor Pullup
        3. 8.1.4.3 Combination Pullup
      5. 8.1.5 RF Output Treatment for the Complimentary Side
        1. 8.1.5.1 Single-Ended Termination of Unused Output
        2. 8.1.5.2 Differential Termination
      6. 8.1.6 External Loop Filter
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  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 Device Support
      1. 11.1.1 Development Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

7.3.9 Output Buffer

The RF output buffer type is open-collector that requires an external pullup to VCC. This component may be a 50-Ω resistor or an inductor. The inductor has less controlled impedance, but higher power. For the inductor case, it is often helpful to follow this with a resistive pad. The output power can be programmed to various levels or disabled while still keeping the PLL in lock.

Table 7-10 OUTx_PWR Recommendations
fOUTRESTRICTIONSCOMMENTS
10 MHz ≤ fOUT ≤ 5 GHzNoneAt lower frequencies, the output buffer impedance is high, so the 50-Ω pullup will make the output impedance look somewhat like 50 Ω.
5 GHz ≤ fOUT ≤ 10 GHzOUTx_PWR ≤ 31In this range, parasitic inductances have some impact, so the output setting is restricted.
10 GHz < fOUTOUTx_PWR ≤ 20At these higher frequency ranges, it is best to keep below 20 for highest power and optimal noise floor.