An ISO 26262 hardware metric expressing how small the share of single-point faults (which alone violate a safety goal) and residual faults is among safety-related faults. Typical targets are at least 90% for ASIL B, 97% for ASIL C and 99% for ASIL D.
Japanese name: SPFM(単一点故障指標)
SPFM (single-point fault metric) appears in 4 practice questions across 1 topic, including Automotive Semiconductors and Functional Safety.
Answer: C. 99% or higher
SPFM indicates how few of the safety-related faults are single-point faults, which by themselves lead to violation of a safety goal, or residual faults, which remain undetected by safety mechanisms; it is calculated as 1 minus the proportion of their combined failure rate. Target guidelines are 90% or higher for ASIL B, 97% or higher for ASIL C and 99% or higher for ASIL D. The latent fault metric (LFM) guidelines are 60% or higher for ASIL B, 80% or higher for ASIL C and 90% or higher for ASIL D, so 90% and 60% are easily confused with LFM or ASIL B values.
Answer: A. 99.5%
SPFM is calculated as 1 minus the "sum of the single-point and residual fault failure rates" divided by the "total safety-related failure rate." In this example, 1 − 5 / 1000 = 1 − 0.005 = 0.995, or 99.5%. This meets the ASIL D guideline of 99% or higher. 95% is the value obtained by overestimating the proportion by an order of magnitude, and 99.95% by underestimating it by an order of magnitude. To raise SPFM, add safety mechanisms with high diagnostic coverage to reduce faults that remain undetected.
SPFM indicates how few of the safety-related faults are single-point faults, which by themselves lead to violation of a safety goal, or residual faults, which remain undetected by safety mechanisms; it is calculated as 1 minus the proportion of their combined failure rate.
Which is the correct target guideline for the single-point …SPFM is calculated as 1 minus the "sum of the single-point and residual fault failure rates" divided by the "total safety-related failure rate." In this example, 1 − 5 / 1000 = 1 − 0.005 = 0.995, or 99.5%.
The total failure rate of safety-related hardware is 1000 F…Random hardware failures, such as component degradation or bit flips from cosmic rays, are failures whose occurrence can be predicted only probabilistically; they are evaluated quantitatively with failure rates (FIT) using metrics such as SPFM and PMHF.
Which correctly pairs the descriptions of random hardware f…From the results, SPFM, LFM and PMHF are calculated, and safety mechanisms are added if the targets are not met.
Which correctly describes FMEDA (Failure Modes, Effects and…As an Amazon Associate I earn from qualifying purchases.
ASIL (Automotive Safety Integrity Level) Safety goal Diagnostic coverage ISO 26262 FMEA (failure mode and effects analysis) AEC-Q100 CAN bus ECU (electronic control unit) FTTI (fault tolerant time interval) HARA (hazard analysis and risk assessment)