ZHCSH72I September   2011  – December 2017 LMK00301

PRODUCTION DATA.  

  1. 特性
  2. 应用
  3. 说明
    1.     Device Images
      1.      功能框图
      2.      LVPECL 输出摆幅 (VOD) 与频率间的关系
  4. 修订历史记录
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. Parameter Measurement Information
    1. 8.1 Differential Voltage Measurement Terminology
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
      1. 9.2.1 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 VCC and VCCO Power Supplies
      2. 9.3.2 Clock Inputs
      3. 9.3.3 Clock Outputs
        1. 9.3.3.1 Reference Output
  10. 10Application and Implementation
    1. 10.1 Driving the Clock Inputs
    2. 10.2 Crystal Interface
    3. 10.3 Termination and Use of Clock Drivers
      1. 10.3.1 Termination for DC Coupled Differential Operation
      2. 10.3.2 Termination for AC Coupled Differential Operation
      3. 10.3.3 Termination for Single-Ended Operation
  11. 11Power Supply Recommendations
    1. 11.1 Power Supply Sequencing
    2. 11.2 Current Consumption and Power Dissipation Calculations
      1. 11.2.1 Power Dissipation Example #1: Separate Vcc and Vcco Supplies with Unused Outputs
      2. 11.2.2 Power Dissipation Example #2: Worst-Case Dissipation
    3. 11.3 Power Supply Bypassing
      1. 11.3.1 Power Supply Ripple Rejection
    4. 11.4 Thermal Management
  12. 12器件和文档支持
    1. 12.1 文档支持
      1. 12.1.1 相关文档
    2. 12.2 社区资源
    3. 12.3 商标
    4. 12.4 静电放电警告
    5. 12.5 Glossary
  13. 13机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

Power Dissipation Example #2: 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 maximum supply current and power calculations from the previous section, we can compute PTOTAL and PDEVICE.

  • From Equation 5: ICC_TOTAL = 10.5 mA + 27 mA + 27 mA + 5.5 mA = 70 mA
  • From ICCO_PECL max spec: ICCO_BANK_A = ICCO_BANK_B = 197 mA
  • From Equation 7: PTOTAL = 3.465 V * (70 mA + 197 mA + 197 mA + 10 mA) = 1642.4 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 = 1642.4 mW - (10 * (25.5 mW + 39.5 mW)) - 0 mW = 992.4 mW

In this worst-case example, the IC device will dissipate about 992.4 mW or 60% of the total power (1642.4 mW), while the remaining 40% will be dissipated in the LVPECL emitter resistors (255 mW for 10 pairs) and termination voltage (395 mW into Vcco - 2 V).

Based on θJA of 28.5 °C/W, the estimated die junction temperature would be about 28.3 °C above ambient, or 113.3 °C when TA = 85 °C.