SNAS601G August   2012  – September 2014 LMX2581

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Revision History
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 Handling Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements, MICROWIRE Timing
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Typical Performance Characteristics
        1. 8.3.1.1 Phase Noise Typical Performance Plot Explanations
        2. 8.3.1.2 Other Typical Performance Plot Characteristics Explanations
      2. 8.3.2  Impact of Temperature on VCO Phase Noise
      3. 8.3.3  OSCin INPUT and OSCin Doubler
      4. 8.3.4  R Divider
      5. 8.3.5  PLL N Divider And Fractional Circuitry
        1. 8.3.5.1 Programmable Dithering Levels
        2. 8.3.5.2 Programmable Delta Sigma Modulator Order
      6. 8.3.6  PLL Phase Detector and Charge Pump
      7. 8.3.7  External Loop Filter
      8. 8.3.8  Low Noise, Fully Integrated VCO
        1. 8.3.8.1 VCO Digital Calibration
      9. 8.3.9  Programmable VCO Divider
      10. 8.3.10 0-Delay Mode
      11. 8.3.11 Programmable RF Output Buffers
        1. 8.3.11.1 Choosing the Proper Pull-Up Component
        2. 8.3.11.2 Choosing the Best Setting for the RFoutA_PWR and RFoutB_PWR Words
      12. 8.3.12 Fastlock
      13. 8.3.13 Lock Detect
        1. 8.3.13.1 Vtune Lock Detect
        2. 8.3.13.2 Digital Lock Detect (DLD)
      14. 8.3.14 Part ID and Register Readback
        1. 8.3.14.1 Uses of Readback
        2. 8.3.14.2 Serial Timing for Readback
      15. 8.3.15 Optimization of Spurs
        1. 8.3.15.1 Phase Detector Spur
        2. 8.3.15.2 Fractional Spur - Integer Boundary Spur
        3. 8.3.15.3 Fractional Spur - Primary Fractional Spurs
        4. 8.3.15.4 Fractional Spur - Sub-Fractional Spurs
        5. 8.3.15.5 Summary of Spurs and Mitigation Techniques
    4. 8.4 Device Functional Modes
      1. 8.4.1 Full Synthesizer Mode
      2. 8.4.2 External VCO Mode
      3. 8.4.3 Powerdown Modes
    5. 8.5 Programming
      1. 8.5.1 Serial Data Input Timing
      2. 8.5.2 Recommended Initial Power on Programming Sequence
      3. 8.5.3 Recommended Sequence for Changing Frequencies
      4. 8.5.4 Triggering Registers
    6. 8.6 Register Maps
      1. 8.6.1 Programming Word Descriptions
        1. 8.6.1.1  Register R15
          1. 8.6.1.1.1 VCO_CAP_MAN — Manual VCO Band Select
          2. 8.6.1.1.2 VCO_CAPCODE[7:0] — Capacitor Value for VCO Band Selection
        2. 8.6.1.2  Register R13
          1. 8.6.1.2.1 DLD_ERR_CNT[3:0] - Digital Lock Detect Error Count
          2. 8.6.1.2.2 DLD_PASS_CNT[9:0] - Digital Lock Detect Success Count
          3. 8.6.1.2.3 DLD_TOL[2:0] — Digital Lock Detect
        3. 8.6.1.3  Registers R10, R9, and R8
        4. 8.6.1.4  Register R7
          1. 8.6.1.4.1 FL_PINMODE[2:0], MUXOUT_PINMODE[2:0], and LD_PINMODE[2:0] — Output Format for Status Pins
          2. 8.6.1.4.2 FL_INV, MUX_INV, LD_INV - Inversion for Status Pins
          3. 8.6.1.4.3 FL_SELECT[4:0], MUXOUT_SELECT[4:0], LD_SELECT[4:0] — State for Status Pins
        5. 8.6.1.5  Register R6
          1. 8.6.1.5.1 RD_DIAGNOSTICS[19:0] — Readback Diagnostics
          2. 8.6.1.5.2 RDADDR[3:0] — Readback Address
          3. 8.6.1.5.3 uWIRE_LOCK - Microwire lock
        6. 8.6.1.6  Register R5
          1. 8.6.1.6.1  OUT_LDEN — Mute Outputs Based on Lock Detect
          2. 8.6.1.6.2  OSC_FREQ[2:0] — OSCin Frequency for VCO Calibration
          3. 8.6.1.6.3  BUFEN_DIS - Disable for the BUFEN Pin
          4. 8.6.1.6.4  VCO_SEL_MODE — Method of Selecting Internal VCO Core
          5. 8.6.1.6.5  OUTB_MUX — Mux for RFoutB
          6. 8.6.1.6.6  OUTA_MUX — Mux for RFoutA
          7. 8.6.1.6.7  0_DLY - Zero Delay Mode
          8. 8.6.1.6.8  MODE[1:0] — Operating Mode
          9. 8.6.1.6.9  PWDN_MODE - Powerdown Mode
          10. 8.6.1.6.10 RESET - Register Reset
        7. 8.6.1.7  Register R4
          1. 8.6.1.7.1 PFD_DLY[2:0] — Phase Detector Delay
          2. 8.6.1.7.2 FL_FRCE — Force Fastlock Conditions
          3. 8.6.1.7.3 FL_TOC[11:0] — Fastlock Timeout Counter
          4. 8.6.1.7.4 FL_CPG[4:0] — Fastlock Charge Pump Gain
          5. 8.6.1.7.5 CPG_BLEED[5:0]
        8. 8.6.1.8  Register R3
          1. 8.6.1.8.1 VCO_DIV[4:0] — VCO Divider Value
          2. 8.6.1.8.2 OUTB_PWR[5:0] — RFoutB Output Power
          3. 8.6.1.8.3 OUTA_PWR[5:0] — RFoutA Output Power
          4. 8.6.1.8.4 OUTB_PD — RFoutB Powerdown
          5. 8.6.1.8.5 OUTA_PD — RFoutA Powerdown
        9. 8.6.1.9  Register R2
          1. 8.6.1.9.1 OSC_2X — OSCin Doubler
          2. 8.6.1.9.2 CPP - Charge Pump Polarity
          3. 8.6.1.9.3 PLL_DEN[21:0] — PLL Fractional Denominator
        10. 8.6.1.10 Register R1
          1. 8.6.1.10.1 CPG[4:0] — PLL Charge Pump Gain
          2. 8.6.1.10.2 VCO_SEL[1:0] - VCO Selection
          3. 8.6.1.10.3 FRAC_ORDER[2:0] — PLL Delta Sigma Modulator Order
          4. 8.6.1.10.4 PLL_R[7:0] — PLL R divider
        11. 8.6.1.11 Register R0
          1. 8.6.1.11.1 ID - Part ID Readback
          2. 8.6.1.11.2 FRAC_DITHER[1:0] — PLL Fractional Dithering
          3. 8.6.1.11.3 NO_FCAL — Disable Frequency Calibration
          4. 8.6.1.11.4 PLL_N - PLL Feedback Divider Value
          5. 8.6.1.11.5 PLL_NUM[21:12] and PLL_NUM[11:0] — PLL Fractional Numerator
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Clocking Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Fractional PLL Application
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
    3. 9.3 Do's and Don'ts
  10. 10Power Supply Recommendations
    1. 10.1 Supply Recommendations
    2. 10.2 Regulator Output Pins
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

12 Device and Documentation Support

12.1 Device Support

Texas Instruments has several software tools available at :

  • See Codeloader to understand how to program the LMX2581 and the EVM board.
  • See Clock Design Tool for designing loop filters, simulating phase noise, and simulating spurs on the LMX2581.
  • See the EVM Board instructions, SNAU136, for typical measured data, detailed measurement conditions, and a complete design.
  • See Clock Architect for designing and simulating the LMX2581 and understanding how it might work with other devices.

12.2 Documentation Support

12.2.1 Related Documentation

See also "AN-1879 Fractional N Frequency Synthesis" (SNAA062).

12.3 Trademarks

All other trademarks are the property of their respective owners.

12.4 Electrostatic Discharge Caution

esds-image

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates.

12.5 Glossary

SLYZ022 — TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.