Functional safety
What is the difference between SIL and ASIL?
LAST REVIEWED
| SIL (IEC 61508) | ASIL (ISO 26262) | |
|---|---|---|
| Scope | Any E/E/PE safety-related system | Road vehicle E/E systems |
| Levels | SIL 1–4 | QM, ASIL A–D |
| Derived from | Required risk reduction, expressed as a target failure measure | Severity, exposure and controllability ratings |
| Applies to | A specific safety function in a specific application | A safety goal, inherited by requirements and elements |
There is no valid conversion table between the two. A supplier claim that a component is 'SIL 2, equivalent to ASIL B' is a commercial shorthand, not a conformity argument: the target still has to be justified from the hazard analysis of the actual application.
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