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

10.2.1 Power Dissipation Example: Worst-Case Dissipation

This example shows how to calculate IC power dissipation for a configuration to estimate worst-case power dissipation. In this case, the maximum supply voltage and supply current values specified in Electrical Characteristics are used.

  • Max VCC = VCCO = 3.465 V. Max ICC and ICCO values.
  • CLKin0/CLKin0* input is selected.
  • Banks A and B are configured for LVPECL: all outputs terminated with 50 Ω to VT = Vcco – 2 V.
  • REFout is enabled with 5-pF load.
  • TA = 85°C

Using the power calculations from the previous section and maximum supply current specifications, we can compute PTOTAL and PDEVICE.

  • From Equation 5: ICC_TOTAL = 10.5 mA + 48 mA + 5.5 mA = 64 mA
  • From ICCO_PECL max spec: ICCO_BANK = 50% of ICCO_PECL = 81.5 mA
  • From Equation 7: PTOTAL = (3.465 V × 64 mA) + (3.465 V × 81.5 mA)+ (3.465 V × 81.5 mA) + (3.465 V × 10 mA) = 821 mW
  • From Equation 8: PRT_PECL = ((2.57 V – 1.47 V)2/50 Ω) + ((1.72 V – 1.47 V)2/50 Ω) = 25.5 mW (per output pair)
  • From Equation 9: PVTT_PECL = 1.47 V × [ ((2.57 V – 1.47 V) / 50 Ω) + ((1.72 V – 1.47 V) / 50 Ω) ] = 39.5 mW (per output pair)
  • From Equation 10: PRT_HCSL = 0 mW (no HCSL outputs)
  • From Equation 11: PDEVICE = 821 mW – (4 × (25.5 mW + 39.5 mW)) – 0 mW = 561 mW

In this worst-case example, the IC device will dissipate about 561 mW or 68% of the total power (821 mW), while the remaining 32% will be dissipated in the emitter resistors (102 mW for 4 pairs) and termination voltage (158 mW into Vcco – 2 V). Based on θJA of 38.1°C/W, the estimate die junction temperature would be about 21.4°C above ambient, or 106.4°C when TA = 85°C.