SNAS824B October   2021  – June 2022 LMX2571-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  Differences Between the LMX2571 and LMX2571-EP
      2. 7.3.2  Reference Oscillator Input
      3. 7.3.3  R-Dividers and Multiplier
      4. 7.3.4  PLL Phase Detector and Charge Pump
        1. 7.3.4.1 CPout Pin Charge Pump Current
        2. 7.3.4.2 Charge Pump Current When Using External VCO
      5. 7.3.5  PLL N-Divider and Fractional Circuitry
      6. 7.3.6  Partially Integrated Loop Filter
      7. 7.3.7  Low-Noise, Fully Integrated VCO
      8. 7.3.8  External VCO Support
      9. 7.3.9  Programmable RF Output Divider
      10. 7.3.10 Programmable RF Output Buffer
      11. 7.3.11 Integrated TX, RX Switch
      12. 7.3.12 Power Down
      13. 7.3.13 Lock Detect
      14. 7.3.14 FSK Modulation
      15. 7.3.15 FastLock
      16. 7.3.16 Register Readback
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation Mode
      2. 7.4.2 Duplex Mode
      3. 7.4.3 FSK Mode
    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  R60 Register (offset = 3Ch) [reset = 4000h]
      2. 7.6.2  R58 Register (offset = 3Ah) [reset = C00h]
      3. 7.6.3  R53 Register (offset = 35h) [reset = 2802h]
      4. 7.6.4  R47 Register (offset = 2Fh) [reset = 0h]
      5. 7.6.5  R46 Register (offset = 2Eh) [reset = 1Ah]
      6. 7.6.6  R42 Register (offset = 2Ah) [reset = 210h]
      7. 7.6.7  R41 Register (offset = 29h) [reset = 810h]
      8. 7.6.8  R40 Register (offset = 28h) [reset = 101Ch]
      9. 7.6.9  R39 Register (offset = 27h) [reset = 11F0h]
      10. 7.6.10 R35 Register (offset = 23h) [reset = 647h]
      11. 7.6.11 R34 Register (offset = 22h) [reset = 1000h]
      12. 7.6.12 R33 Register (offset = 21h) [reset = 0h]
      13. 7.6.13 R25 to R32 Register (offset = 19h to 20h) [reset = 0h]
      14. 7.6.14 R24 Register (offset = 18h) [reset = 10h]
      15. 7.6.15 R23 Register (offset = 17h) [reset = 10A4h]
      16. 7.6.16 R22 Register (offset = 16h) [reset = 8584h]
      17. 7.6.17 R21 Register (offset = 15h) [reset = 101h]
      18. 7.6.18 R20 Register (offset = 14h) [reset = 28h]
      19. 7.6.19 R19 Register (offset = 13h) [reset = 0h]
      20. 7.6.20 R18 Register (offset = 12h) [reset = 0h]
      21. 7.6.21 R17 Register (offset = 11h) [reset = 0h]
      22. 7.6.22 R9 to R16 Register (offset = 9h to 10h) [reset = 0h]
      23. 7.6.23 R8 Register (offset = 8h) [reset = 10h]
      24. 7.6.24 R7 Register (offset = 7h) [reset = 10A4h]
      25. 7.6.25 R6 Register (offset = 6h) [reset = 8584h]
      26. 7.6.26 R5 Register (offset = 5h) [reset = 101h]
      27. 7.6.27 R4 Register (offset = 4h) [reset = 28h]
      28. 7.6.28 R3 Register (offset = 3h) [reset = 0h]
      29. 7.6.29 R2 Register (offset = 2h) [reset = 0h]
      30. 7.6.30 R1 Register (offset = 1h) [reset = 0h]
      31. 7.6.31 R0 Register (offset = 0h) [reset = 3h]
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Direct Digital FSK Modulation
      2. 8.1.2  Frequency and Output Port Switching
      3. 8.1.3  OSCin Configuration
      4. 8.1.4  Register R0 F1F2_INIT, F1F2_MODE Usage
      5. 8.1.5  FastLock With External VCO
      6. 8.1.6  OSCin Slew Rate
      7. 8.1.7  RF Output Buffer Power Control
      8. 8.1.8  RF Output Buffer Type
      9. 8.1.9  MULT Multiplier
      10. 8.1.10 Integrated VCO
    2. 8.2 Typical Applications
      1. 8.2.1 Synthesizer Duplex Mode
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Synthesizer Duplex Mode Application Curves
      2. 8.2.2 PLL Duplex Mode
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 PLL Duplex Mode Application Curves
      3. 8.2.3 Synthesizer/PLL Duplex Mode
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
        3. 8.2.3.3 Synthesizer/PLL Duplex Mode Application Curves
    3. 8.3 Do's and Don'ts
  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

Package Options

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

7.3.5 PLL N-Divider and Fractional Circuitry

The total N-divider value is determined by Ninteger + NUM / DEN. The N-divider includes fractional compensation and can achieve any fractional denominator (DEN) from 1 to 16,777,215 (224 – 1). The integer portion, Ninteger, is the whole part of the N-divider value and the fractional portion, Nfrac = NUM / DEN, is the remaining fraction. Ninteger, NUM and DEN are programmable.

The order of the delta sigma modulator is also programmable from integer mode to fourth order. There are several dithering modes that are also programmable. Dithering is used to reduce fractional spurs. In order to make the fractional spurs consistent, the modulator is reset any time that the R0 register is programmed.