1 Functional Safety Standards and Levels
Functional safety refers to a system's ability to detect faults and failures and to handle them safely. If a occurs without being detected, serious consequences, such as injury, loss of life, or property damage could occur. Functional safety is crucial in various industries, including automotive, industrial, household/home appliances, medical, nuclear and manufacturing. It encompasses the identification and mitigation of risks associated with the operation of machinery, equipment, and processes.
Microchip supports three major functional safety standards: ISO 26262 (Automotive), IEC 61508 (Industrial), and IEC 60730 (Home Appliances). Each of these standards defines safety levels, helping quantify the safety function reliability within a system. When designing a system, each component or sub-system should be designed with the system’s highest safety level in mind.
For automotive, industrial and home appliance sectors, these safety levels are defined as Automotive Safety Integrity Level (ASIL A, B, C, D), Safety Integrity Level (SIL 1, 2, 3, 4), and Class A, B, C, respectively. In automotive applications, ASIL A represents the lowest degree of automotive hazard, while ASIL D represents the highest. Similarly, in industrial and household applications, SIL 1 represents the lowest degree of hazard, while SIL 4 represents the highest, and Class A represents the lowest while Class C represents the highest. When systems related to the safety of the user or environment fall below ASIL A, SIL 1 or Class A, often it is classified as “Quality Managed”, which means the original equipment manufacturer should still design this system to be of the utmost quality to ensure safety.
Functional safety standards typically advise developers on the following: Safety lifecycle, safety integrity levels, risk assessments, safety requirements, verifications and validations, documentation and compliance, organizational requirements, change of management, and more. Overall, Functional safety helps ensure that safety-critical systems and processes operate reliably and mitigate the risk of accidents, incidents, and harm to people, property, and the environment.