The Automotive Safety Integrity Level (ASIL) expresses the criticality associated with a function of the system. It defines the safety requirements that must be fulfilled by the design and development of the system in such a way that, even in conditions of failure, the system provides a sufficient margin of safety for the users (driver, passengers, road traffic participants, etc.). Under certain circumstances, the ASIL can be lowered through the technique of ASIL decomposition.
The following table displays valid ASIL decomposition combinations:
ASIL value | ASIL decomposition combinations | ||
---|---|---|---|
D | C(D) + A(D) | B(D) + B(D) | D(D) + QM(D) |
D(D) | C(D) + A(D) | B(D) + B(D) | D(D) + QM(D) |
C | B(C) + A(C) | C(C) + QM(C) | |
C(D) | B(D) + A(D) | C(D) + QM(D) | |
C(C) | B(C) + A(C) | C(C) + QM(C) | |
B | A(B) + A(B) | B(B) + QM(B) | |
B(D) | A(D) + A(D) | B(D) + QM(D) | |
B(C) | A(C) + A(C) | B(C) + QM(C) | |
B(B) | A(B) + A(B) | B(B) + QM(B) | |
A | A(A) + QM(A) | ||
A(D) | A(D) + QM(D) | ||
A(C) | A(C) + QM(C) | ||
A(B) | A(B) + QM(B) | ||
A(A) | A(A) + QM(A) |
To decompose an ASIL value
After completing the above steps, your diagram should look similar to the sample diagram shown below.