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

2.1.1 Fault Rate Estimation Theory for Packaging

TI uses the IEC/TR 62380 model to estimate package FIT rate for the DMT package used for this device. The IEC/TR 62380 package model is primarily concerned with wear-out due to thermal expansion between the package and the PCB. The model includes several variables that have been replaced with device-specific data when available, such as power consumption and package thermal characteristics. It is highly recommended that the user applies their own application mission profile in the 'Mission Profile Tailoring' tab as this has a large impact on the base package FIT rate. The automotive motor control profile is used as the default in TI's estimates.

Note:

TI field data in high volume automotive and industrial applications indicates a random package failure rate and a silicon permanent fault rate that is at least two orders of magnitude lower than the estimates generated using the IEC/TR 62380. TI devices are designed with a high degree of margin to the wear out failure mechanisms respected in IEC/TR 62380; most applications will not approach the wear-out limits within product lifetime. It has also been argued that wear-out mechanisms should be considered a systematic failure mode and as such should not be included in safety metric analysis. Data generated using the IEC/TR 62380 standard should be considered conservative estimates.