Cadence maps out safety plan for semiconductor-design tools

Cadence Design Systems is nearing completion of a program that will provide a portfolio of documentation for users of its tools who need to obtain safety approvals for their designs.

The EDA company enlisted the help of standards and accreditation specialist TÜV Süd to put together packages of documentation for its mixed-signal and digital flows that, if used in the approved way, provide assurance to Tool Confidence Level 1 (TCL1) of the ISO 26262 standard.

The TCL is a measure of the level of risk involved with using a particular tool – identifying whether it is capable of introducing safety hazards through internal malfunctions or errors. As the highest level of confidence TCL1 means errors in the tool code will not cause safety violations.

“The TCL1 pre-qualification process allows us to say ‘if you use the tools in the manner we have defined, this is the highest level that’s achievable’,” said John Brennan, product marketing director at Cadence. “We will be supporting over 30 tools by the end of the year. But it is modular and flexible enough to accommodate customers’ own tooling or tools from third parties.”

Effects table

To put together the documentation package, Brennan said: “What we ended up doing was create a failure mode and effects analysis table for each tool. The table shows that to use this tool in a way that it won’t inject a safety hazard by itself these are the things you should be doing.

“If there is a failure mode, we define the possible avoidance recommendations that a user can apply. We provide use-cases and argumentation around the scenarios. With that backup they are in a very good position to achieve TCL1 determination with their auditor,” Brennan claimed. “It’s there to make the documentation process easier for our customers.”

To put together the documentation, Cadence split the work into three phases, starting off with a package for mixed-signal flows that acted as a pipe-cleaner for the process the company worked out with TÜV Süd. This was followed by one for digital front-end design and verification that includes documentation for the simulators and emulators in Cadence’s lineup. The last piece, to be completed by the end of the year, is for digital implementation and signoff.

“We will post online as we get new updates,” Brennan said. “We will continue to enhance the package to support more esoteric use-cases that we didn’t think about initially.”