SNAS577G February   2012  – August 2018 LMK00304

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Functional Block Diagram
      2.      LVPECL Output Swing (VOD) vs. Frequency
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Differential Voltage Measurement Terminology
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 VCC and VCCO Power Supplies
      2. 8.3.2 Clock Inputs
      3. 8.3.3 Clock Outputs
        1. 8.3.3.1 Reference Output
  9. 9 Application and Implementation
    1. 9.1 Driving the Clock Inputs
    2. 9.2 Crystal Interface
    3. 9.3 Termination and Use of Clock Drivers
      1. 9.3.1 Termination for DC-Coupled Differential Operation
      2. 9.3.2 Termination for AC-Coupled Differential Operation
      3. 9.3.3 Termination for Single-Ended Operation
  10. 10Power Supply Recommendations
    1. 10.1 Power Supply Sequencing
    2. 10.2 Current Consumption and Power Dissipation Calculations
      1. 10.2.1 Power Dissipation Example: Worst-Case Dissipation
    3. 10.3 Power Supply Bypassing
      1. 10.3.1 Power Supply Ripple Rejection
    4. 10.4 Thermal Management
      1. 10.4.1 Support for PCB Temperature up to 105°C
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.1 Differential Voltage Measurement Terminology

The differential voltage of a differential signal can be described by two different definitions causing confusion when reading datasheets or communicating with other engineers. This section will address the measurement and description of a differential signal so that the reader will be able to understand and discern between the two different definitions when used.

The first definition used to describe a differential signal is the absolute value of the voltage potential between the inverting and non-inverting signal. The symbol for this first measurement is typically VID or VOD depending on if an input or output voltage is being described.

The second definition used to describe a differential signal is to measure the potential of the non-inverting signal with respect to the inverting signal. The symbol for this second measurement is VSS and is a calculated parameter. Nowhere in the IC does this signal exist with respect to ground, it only exists in reference to its differential pair. VSS can be measured directly by oscilloscopes with floating references, otherwise this value can be calculated as twice the value of VOD as described in the first description.

Figure 23 illustrates the two different definitions side-by-side for inputs and Figure 24 illustrates the two different definitions side-by-side for outputs. The VID (or VOD) definition show the DC levels, VIH and VOL (or VOH and VOL), that the non-inverting and inverting signals toggle between with respect to ground. VSS input and output definitions show that if the inverting signal is considered the voltage potential reference, the non-inverting signal voltage potential is now increasing and decreasing above and below the non-inverting reference. Thus the peak-to-peak voltage of the differential signal can be measured.

VID and VOD are often defined as volts (V) and VSS is often defined as volts peak-to-peak (VPP).

LMK00304 30177307.gifFigure 23. Two Different Definitions for Differential Input Signals
LMK00304 30177308.gifFigure 24. Two Different Definitions for Differential Output Signals

Refer to Application Note AN-912 Common Data Transmission Parameters and their Definitions (SNLA036) for more information.