SNAS866A December   2023  – September 2024 LMX1214

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Timing Diagram
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
      1. 6.1.1 Range of Dividers
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Power-On Reset
      2. 6.3.2 Temperature Sensor
      3. 6.3.3 Clock Outputs
        1. 6.3.3.1 Clock Output Buffers
        2. 6.3.3.2 Clock MUX
        3. 6.3.3.3 Clock Divider
      4. 6.3.4 AUXCLK Output
        1. 6.3.4.1 AUXCLKOUT Output Format
        2. 6.3.4.2 AUXCLK_DIV_PRE and AUXCLK_DIV Dividers
      5. 6.3.5 SYNC Input Pins
        1. 6.3.5.1 SYNC Pins Common-Mode Voltage
        2. 6.3.5.2 Windowing Feature
    4. 6.4 Device Functional Modes Configurations
      1. 6.4.1 Pin Mode Control
  8. 7 Register Map
    1. 7.1 Device Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 SYNC Input Configuration
      2. 8.1.2 Treatment of Unused Pins
      3. 8.1.3 Current Consumption
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Plots
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Tape and Reel Information

8.1.1 SYNC Input Configuration

The SYNC pins support single-ended or differential input in AC or DC coupling mode. The SYNC pins have an internal 50-Ω termination with capacitive ground, which acts as 100-Ω differential.

Figure 8-1 shows the generic SYNC input circuit recommendation to support all AC or DC, single-ended or differential inputs. Some of the discrete components in fig are just placeholder for individual input signal (single-ended or differential input) and AC or DC coupled input.

LMX1214 SYNC Input Circuit Recommendations Figure 8-1 SYNC Input Circuit Recommendations

The following figures show the individual circuit diagram for each configurations:

LMX1214 AC-Coupled Differential InputFigure 8-2 AC-Coupled Differential Input
LMX1214 DC-Coupled Differential InputFigure 8-4 DC-Coupled Differential Input
LMX1214 AC-Coupled, Single-Ended InputFigure 8-3 AC-Coupled, Single-Ended Input
LMX1214 DC-Coupled, Single-Ended InputFigure 8-5 DC-Coupled, Single-Ended Input
  1. AC coupled differential and single-ended input configurations required the resistor terminations (R2 and R3) to create the VCM at each pin and resistor values must select to maintain greater than 150-mV potential difference between pin P and pin N.
    1. As an example, to create the VCM of 1.5 V at pin P and 1.65 V at pin N, with the 2.5 V VCC, set R3 = 550 Ω and R2 = 1 kΩ.
    2. For single-ended input configuration, place R6 = 50 Ω to avoid any reflection at complementary input pin.
  2. DC coupled differential and single-ended input configuration required to have the source common-mode voltage matched with the device input common mode specifications.
    1. For single-ended input configuration, keep the R1, R2, R3 and R4 resistors. This method creates the same common-mode voltage at both pins, and the resistive dividers create 75 Ω at pin P and 50-Ω Thevenin's equivalent at pin N.
    2. As an example, to have the common-mode voltage of 1.35 V at each pin, set the resistive divider components values to R1 = 130 Ω, R2 = 165 Ω, R3 = 86.6 Ω and R4 = 110 Ω with the 2.5-V VCC.