SNAS187D February   2003  – January 2016 LMX2430 , LMX2433 , LMX2434

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description continued
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 Recommended Operating Conditions
    3. 7.3 Thermal Information
    4. 7.4 Electrical Characteristics
    5. 7.5 Timing Requirements
    6. 7.6 Typical Characteristics
      1. 7.6.1 Sensitivity
      2. 7.6.2 Charge Pump
      3. 7.6.3 Input Impedance
  8. 8 Parameter Measurement Information
    1. 8.1 Bench Test Setups
      1. 8.1.1 LMX243x Charge-Pump Test Setup
      2. 8.1.2 Charge-Pump Current Specification Definitions
        1. 8.1.2.1 Charge-Pump Output Current Variation vs Charge-Pump Output Voltage
        2. 8.1.2.2 Charge-Pump Sink Current vs Charge-Pump Output Source Current Mismatch
        3. 8.1.2.3 Charge-Pump Output Current Variation vs Temperature
      3. 8.1.3 LMX243x FinRF Sensitivity Test Setup
      4. 8.1.4 LMX243x OSCin Sensitivity Test Setup
      5. 8.1.5 LMX243x FinRF Input Impedance Test Setup
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Reference Oscillator Input
      2. 9.3.2  Reference Dividers (R Counters)
      3. 9.3.3  Prescalers
      4. 9.3.4  Programmable Feedback Dividers (N Counters)
      5. 9.3.5  Phase / Frequency Detectors
        1. 9.3.5.1 Phase Comparator and Internal Charge-Pump Characteristics
      6. 9.3.6  Charge Pumps
      7. 9.3.7  Microwire Serial Interface
      8. 9.3.8  Multi-Function Outputs
        1. 9.3.8.1 Push-Pull Analog Lock-Detect Output
        2. 9.3.8.2 Open-Drain Analog Lock-Detect Output
        3. 9.3.8.3 Digital Filtered Lock-Detect Output
        4. 9.3.8.4 Reference Divider and Feedback Divider Output
      9. 9.3.9  Fastlock Output
      10. 9.3.10 Counter Reset
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power Control
        1. 9.4.1.1 Synchronous Power-Down Mode
        2. 9.4.1.2 Asynchronous Power-Down Mode
    5. 9.5 Programming
      1. 9.5.1 Microwire Interface
      2. 9.5.2 Control Register Location
    6. 9.6 Register Maps
      1. 9.6.1 Control Register Content Map
      2. 9.6.2 R0 Register
        1. 9.6.2.1 RF_R[14:0] - RF Synthesizer Programmable Reference Divider (R Counter) (R0[17:3])
        2. 9.6.2.2 RF_CPP - RF Synthesizer Phase Detector Polarity (R0[18])
        3. 9.6.2.3 RF_CPG - RF Synthesizer Charge-Pump Current Gain (R0[19])
        4. 9.6.2.4 RF_CPT - RF Synthesizer Charge-Pump Tri-State (R0[20])
        5. 9.6.2.5 RF_RST - RF Synthesizer Counter Reset (R0[21])
      3. 9.6.3 R1 Register
        1. 9.6.3.1 LMX243x RF Synthesizer Swallow Counter
          1. 9.6.3.1.1 RF_A[3:0] - LMX2430/33 RF Synthesizer Swallow Counter (A Counter) (R1[6:3])
          2. 9.6.3.1.2 RF_A[4:0] - LMX2434 RF Synthesizer Swallow Counter (A Counter) (R1[7:3])
        2. 9.6.3.2 LMX243x RF Synthesizer Programmable Binary Counter
          1. 9.6.3.2.1 RF_B[14:0] - LMX2430/33 RF Synthesizer Programmable Binary Counter (B Counter) (R1[21:7])
          2. 9.6.3.2.2 RF_B[13:0] - LMX2434 RF Synthesizer Programmable Binary Counter (B Counter) (R1[21:8])
        3. 9.6.3.3 LMX243x RF Synthesizer Prescaler Select
          1. 9.6.3.3.1 RF_P - LMX2430/33 RF Synthesizer Prescaler Select (R1[22])
          2. 9.6.3.3.2 RF_P - LMX2434 RF Synthesizer Prescaler Select (R1[22])
        4. 9.6.3.4 RF_PD - RF Synthesizer Power Down (R1[23])
      4. 9.6.4 R2 Register
        1. 9.6.4.1 RF_TOC[0:11] - RF Synthesizer Time-Out Counter (R2[14:3])
        2. 9.6.4.2 R3 Register
          1. 9.6.4.2.1 IF_R[14:0] - IF Synthesizer Programmable Reference Divider (R Counter) (R3[17:3])
          2. 9.6.4.2.2 IF_CPP - IF Synthesizer Phase Detector Polarity (R3[18])
          3. 9.6.4.2.3 IF_CPG - IF Synthesizer Charge-Pump Current Gain (R3[19])
          4. 9.6.4.2.4 IF_CPT - IF Synthesizer Charge-Pump Tri-State (R3[20])
          5. 9.6.4.2.5 IF_RST - IF Synthesizer Counter Reset (R3[21])
      5. 9.6.5 R4 Register
        1. 9.6.5.1 IF_A[3:0] - IF Synthesizer Swallow Counter (A Counter) (R4[6:3])
        2. 9.6.5.2 IF_B[13:0] - IF Synthesizer Programmable Binary Counter (B Counter) (R4[20:7])
          1. 9.6.5.2.1 IF_P - IF Synthesizer Prescaler Select (R4[22])
        3. 9.6.5.3 IF_PD - IF Synthesizer Power Down (R4[23])
      6. 9.6.6 R5 Register
        1. 9.6.6.1 IF_TOC[0:11] - IF Synthesizer Time-Out Counter (R5[14:3])
      7. 9.6.7 MUX[3:0] - Multifunction Output Select (R3[23:22]:R0[23:22])
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Device Nomenclature
        1. 13.1.1.1 List of Definitions
    2. 13.2 Related Links
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

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10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

10.1 Application Information

The LMX2430 family of devices can be used in a broad class of applications. LMX2430x devices have very low current consumption and are well-suited for many lower power applications. Because these devices have two PLLs, they can be used to generate two distinct frequencies. However, it is a perfectly valid thing to only use one of the PLLs and power down the other side. When only one side is used, be sure to power the other side down, but do NOT disconnect the power pins for the unused side as they are shared across several internal blocks. When the unused side is powered down, it draws no current, and the counters and charge pump are not running or generating any noise and spurs. Figure 33 generally applies to most applications.

10.2 Typical Application

LMX2430 LMX2433 LMX2434 sch_apps_snas187.gif Figure 33. Typical Use Case

10.2.1 Design Requirements

Table 41 lists the design parameters of the LMX243x.

Table 41. Design Parameters

PARAMETER VALUE
KPD Charge-Pump Gain 4 mA
CVCO VCO Input Capacitance 22 pF
fPD Phase Detector Frequency 1 MHz
fOSC OSCin Frequency 100 MHz
BW Loop Bandwidth 31.1 kHz
PM Phase Margin 59.6 degrees
Gamma Gamma 0.9
T3/T1 T3/T1 Ratio 177.1%
C1_RF Loop Filter Components 270 pF
C2_RF 10 nF
C3_RF 1 nF
C4_RF Open
R2_RF 1.8 Ω
R3_RF 820 Ω
R4_RF 0 Ω

10.2.2 Detailed Design Procedure

The loop filter design is key and involves trade-offs between lock time, phase noise, and spurs. The TI website has references and design and simulation tools that can be used to design the loop filter and simulate the performance.

10.2.3 Application Curves

LMX2430 LMX2433 LMX2434 ta_pn_snas187.png Figure 34. Phase Noise
LMX2430 LMX2433 LMX2434 ta_spur_snas187.png Figure 35. Phase Detector Spurs
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