SFFS143 December   2021 TCAN1164-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

2.2.4 Diagnostic Coverage Tab

This tab is informational only. There are no selections the user can make in this tab.

The 'Diagnostic Coverage' tab is the source for the diagnostic groupings that are selected in the 'Pin Level Tailoring' tab and 'Function and Diag Tailoring' tab. Each design block (Part Level) will have one or more diagnostic options (which appear as the drop-down options in those tabs). The FMA values field represents all of the unique diagnostics that are applied when that diagnostic option is selected. The diagnostic detection, diagnostic coverage, and latent coverage fields indicate the diagnostic coverage claimed for each diagnostic option that will be populated into the 'Function and Diag Tailoring' tab when that option is selected.

For each failure mode of a fundamental design element, a diagnostic may be allocated in the safety architecture to detect failures. Often a single diagnostic is able to detect multiple failure modes. Diagnostics may take the form of software-based tests, hardware test structures, or additional logical channels, amongst other possible implementations. Diagnostics may have continuous, periodic, or one time execution. The frequency of necessary diagnostic application should be determined by the system integrator based on relevant safety constraints (such as fault tolerant time interval, desired detection rate, and so forth), which are necessary to support the targeted safety function or safety goal.