SFFS339 December   2022 TLIN1431-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
  4. 3Using the FMEDA Spreadsheet Tool
    1. 3.1 Mission Profile Tailoring Tab
      1. 3.1.1 Geographical Location
      2. 3.1.2 Life Cycle
      3. 3.1.3 Use Case Thermal Management Control (Theta-Ja) and Use Case Power
      4. 3.1.4 Safe vs Non-Safe (Safe Fail Fraction) for Each Component Type
      5. 3.1.5 Analog FIT Distribution Method
      6. 3.1.6 Operational Profile
    2. 3.2 Pin Level Tailoring Tab
    3. 3.3 Function and Diag Tailoring Tab
    4. 3.4 Diagnostic Coverage Tab
    5. 3.5 Customer Defined Diagnostics Tab
    6. 3.6 Totals - ISO26262 Tab
    7. 3.7 Details - ISO26262 Tab
    8. 3.8 Example Calculation of Metrics
      1. 3.8.1 Assumptions of Use for Calculation of Safety Metrics
      2. 3.8.2 Summary of ISO 26262 Safety Metrics at Device Level

3.1.2 Life Cycle

The default vehicle lifetime field sets the number of hours the vehicle (or system) is in use. This field is not directly used in the FMEDA calculation, however in conjunction with the on time (Ton), this sets the total Power On Hours (POH) which is directly used in the calculation of the raw (base) FIT rate of the device. The user may alter this assumption to meet their specific use case. The longer the vehicle lifetime, a larger number of Power On Hours (POH) are used in the calculation resulting in a larger the raw (base) FIT rate. Please note that for many automotive and industrial devices, this increase in raw (base) FIT rate is too small to be observable in the 'Totals' tabs.