SNAS654A March   2015  – July 2016 LMX2571

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  R-Dividers and Multiplier
      3. 7.3.3  PLL Phase Detector and Charge Pump
      4. 7.3.4  PLL N-Divider and Fractional Circuitry
      5. 7.3.5  Partially Integrated Loop Filter
      6. 7.3.6  Low-Noise, Fully Integrated VCO
      7. 7.3.7  External VCO Support
      8. 7.3.8  Programmable RF Output Divider
      9. 7.3.9  Programmable RF Output Buffer
      10. 7.3.10 Integrated TX, RX Switch
      11. 7.3.11 Powerdown
      12. 7.3.12 Lock Detect
      13. 7.3.13 FSK Modulation
      14. 7.3.14 FastLock
      15. 7.3.15 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 with TrCtl Pin
      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 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

9 Power Supply Recommendations

It is recommended to place 100 nF capacitor close to each of the power supply pins. If fractional spurs are a large concern, using a ferrite bead to each of these power supply pins may reduce spurs to a small degree.

VcpExt is the power supply pin for the 5-V charge pump. In PLL mode, the 5-V charge pump is active and a 5 V is required at VcpExt pin. In synthesizer mode, although the 5-V charge pump is not active, either a 3.3-V or 5-V supply is still needed at this pin.

Because LMX2571 has integrated LDOs, the requirement to external power supply is relaxed. In addition to LDO, LMX2571 is able to operate with DC-DC converter. The switching noise from the DC-DC converter would not affect performance of the LMX2571. Table 45 lists some of the suggested DC-DC converters.

Table 45. Recommended DC-DC Converters

PART NUMBER TOPOLOGY VIN VOUT IOUT SWITCHING FREQUENCY
TPS560200 Buck 4.5 V to 17 V 0.8 V to 6.5 V 500 mA 600 kHz
TPS62050 Buck 2.7 V to 10 V 0.7 V to 6 V 800 mA 1 MHz
TPS62160 Buck 3 V to 17 V 0.9 V to 6 V 1000 mA 2.25 MHz
TPS562200 Buck 4.5 V to 17 V 0.76 V to 7 V 2000 mA 650 kHz
TPS63050 Buck Boost 2.5 V to 5.5 V 2.5 V to 5.5 V 500 mA to 1 A 2.5 MHz