editor's blog
Subscribe Now

Safe Processing

When we recently looked at software and hardware safety standards, much of the discussion was focused on process-oriented standards like DO-254 and DO-178. But we also mentioned some other standards without going into detail. And some of those operate on the concept of “safety integrity level,” or SIL.

The origin of this concept is IEC 61508, which establishes four SILs, numbered 1-4, with 4 indicating the “safest” level. The determination of SIL appears to be relatively complex and somewhat ambiguous since the specific failure modes must be identified for each individual system, and are not codified in IEC 61508. They involve both process considerations as well as the Probability of Failure on Demand, or PFD,  (or its inverse, the Risk Reduction Factor, or RRF).

It’s actually pretty easy to understand the PFD ranges for each SIL: it’s the maximum number of zeros after the decimal for the PFD (or the minimum number of zeros in the RRF). So SIL 1 applies to a PFD of 0.1 to 0.01 (or an RRF of 10 to 100); SIL 4 applies to a PFD of 0.0001-0.00001 (or an RRF of 10,000-100,000).

ISO 26262 has a similar concept for automobiles, referring to Automotive SILs, or ASILs.

Only systems can achieve a SIL level; components may tout a SIL level, but simply using such components (or a process known to have achieved a certain SIL level on a different product) is not sufficient to demonstrate that SIL level. So, for instance, when TI just announced their Hercules microcontrollers, they didn’t say that “these  microcontrollers conform to SIL x.” They listed a series of features that are specifically designed to help a designer achieve a desired SIL or ASIL.

Because these standards don’t call out specific functional requirements, only probabilities of failure and process requirements, the feature list itself can’t be expressly correlated with specifics of the standard. Again, they’re simply things that are known to allow the implementation of safer systems.

More details and the specific features can be found in TI’s release

Leave a Reply

featured blogs
Jan 19, 2021
If you know someone who has a birthday or anniversary or some other occasion coming up, you may consider presenting their present in a Prank-O gift box....
Jan 19, 2021
As promised, we'€™re back with some more of the big improvements that are part of the QIR2 update release of 17.4 (HotFix 013). This time, everything is specific to our Allegro ® Package Designer... [[ Click on the title to access the full blog on the Cadence Communit...
Jan 19, 2021
I'€™ve been reading year-end and upcoming year lists about the future trends affecting technology and electronics. Topics run the gamut from expanding technologies like 5G, AI, electric vehicles, and various realities (XR, VR, MR), to external pressures like increased gover...
Jan 14, 2021
Learn how electronic design automation (EDA) tools & silicon-proven IP enable today's most influential smart tech, including ADAS, 5G, IoT, and Cloud services. The post 5 Key Innovations that Are Making Everything Smarter appeared first on From Silicon To Software....

featured paper

Speeding Up Large-Scale EM Simulation of ICs Without Compromising Accuracy

Sponsored by Cadence Design Systems

With growing on-chip RF content, electromagnetic (EM) simulation of passives is critical — from selecting the right RF design candidates to detecting parasitic coupling. Being on-chip, accurate EM analysis requires a tie in to the process technology with process design kits (PDKs) and foundry-certified EM simulation technology. Anything short of that could compromise the RFIC’s functionality. Learn how to get the highest-in-class accuracy and 10X faster analysis.

Click here to download the whitepaper

Featured Chalk Talk

RX23W Bluetooth

Sponsored by Mouser Electronics and Renesas

Adding Bluetooth to your embedded design can be tricky for IoT developers. Bluetooth 5 brings a host of new capabilities that make Bluetooth integration more compelling than ever. In this episode of Chalk Talk, Amelia Dalton chats with Michael Sarpa from Renesas about the cool capabilities of Bluetooth 5, and how you can easily integrate them into your next project.

More information about Renesas Electronics RX23W 32-bit Microcontrollers