SFFS142 December   2021 TCAN1167-Q1

 

  1.   Trademarks
  2. 1Introduction
  3. 2Hardware Component Failure Modes Effects and Diagnostics Analysis (FMEDA)
    1. 2.1 Random Fault Estimation
      1. 2.1.1 Fault Rate Estimation Theory for Packaging
      2. 2.1.2 Fault Estimation Theory for Silicon Permanent Faults
      3. 2.1.3 Fault Estimation Theory for Silicon Transient Faults
      4. 2.1.4 The Classification of Failure Categories and Calculation
    2. 2.2 Using the FMEDA Spreadsheet Tool
      1. 2.2.1 Mission Profile Tailoring Tab
        1. 2.2.1.1 Confidence Level
        2. 2.2.1.2 Geographical Location
        3. 2.2.1.3 Life Cycle
        4. 2.2.1.4 Use Case Thermal Management Control (Theta-Ja) and Use Case Power
        5. 2.2.1.5 Safe vs Non-Safe (Safe Fail Fraction) for Each Component Type
        6. 2.2.1.6 Analog FIT Distribution Method
        7. 2.2.1.7 Operational Profile
      2. 2.2.2 Pin Level Tailoring Tab
      3. 2.2.3 Function and Diag Tailoring Tab
      4. 2.2.4 Diagnostic Coverage Tab
      5. 2.2.5 Customer Defined Diagnostics Tab
      6. 2.2.6 Totals - ISO26262 Tab
      7. 2.2.7 Details - ISO26262 Tab
    3. 2.3 Example Calculation of Metrics
      1. 2.3.1 Assumptions of Use for Calculation of Safety Metrics
      2. 2.3.2 Summary of ISO 26262 Safety Metrics at Device Level

2.3.1 Assumptions of Use for Calculation of Safety Metrics

A number of assumptions must be made in order to calculate the safety metrics according to ISO 26262:2018. The assumptions of use for the reference are detailed below:

  • Confidence level applied to permanent FIT rates:
  • Confidence level applied to transient FIT rates:
  • Neutron flux: set to 1 (equivalent to exposure at sea level, as measured in New York City)
  • Thermal management (Theta-Ja):
  • Use case power:
  • Safe vs non-safe: All permanent faults are considered 0% safe by default. Transient faults of digital SRAM, digital logic, and flash are considered 50% by default.
  • Operational (mission) profile used:
  • Special considerations on pin level tailoring:
  • Special considerations on function and diag tailoring:
  • Special considerations on the application of diagnostics: