ARM CortexTM-M3 MCU has been specified, designed and analyzed in accordance with functional safety norms IEC61508 and ISO26262

Düsseldorf, Germany, 18th January, 2010 – Toshiba Electronics Europe (TEE) has announced a microcontroller that can be certified to Safety Integrity Level 3 (SIL3) and Automotive SIL D (ASILD) while significantly reducing associated system cost and performance overheads. The Toshiba SIL3/ASILD implementation delivers a more cost- effective solution than alternative methods owing to the fact that it has a smaller chip size, smaller program requirement and better performance than conventional dual-core lock-step methods. It is based on a hardware architecture that reduces both effort of safety mechanisms and their detection latency. Detailed diagnostic information and the ability to configure the reaction according to the severity of the error allow new system concepts to be implemented targeting higher availability.
TEE worked closely with Yogitech SpA, a company specialized in functional safety, and utilized Yogitech’s fRMethodology based assessment flow and library of Intellectual Properties (fRIPs) in its solution. Approved by TÜV SÜD, the fRMethodology is a “white box” approach and it was used to do functional safety analysis and safety-oriented exploration of the Toshiba Target microcontroller unit (MCU) in compliance with IEC 61508 or ISO 26262. The MCU was split into sensitive zones, failure rates were computed and used to calculate safety metrics (for example, to compute the diagnostic coverage) and to decide chip architecture. A detailed validation was done by using fault injection. The fRIPs, certified by
TÜV SÜD, are small hardware supervisors designed with architectural and functional diversity with respect to the MCU sub-block (e.g. CPU, memory) that they supervise. Further peripheral functions on the chip are monitored by Toshiba’s own hardware diagnostic circuits.
Functional safety related system components generally employ duplicated CPU cores (homogenous redundancy): a “mission” core to run the application software and an identical “monitor” core to guard the system against dangerous faults in the mission core. A conventional dual-core lock-step SIL3/ASILD approach has to add further protective features, such as a guard ring, separate supply voltage, synthesis and timing diversity, which increase the chip and program size significantly and impact the system performance. Moreover, homogenous redundancy is very much prone to systematic faults.
The fRMethodology enabled Yogitech to identify critical zones in the mission core, allowing the specification of a monitor core that executes the same instructions as the mission core while excluding unnecessary operations. This process led to the implementation of a diverse and optimized monitor core (the fRCPU), eliminating unnecessary hardware overheads, avoiding systematic faults and also significantly reducing the possibility of common cause failures. The fRCPU version implemented by Toshiba in the MCU is for the ARM Cortex-M3 and it has a gate count up to 58% smaller than is used for the mission core.
The run-time supervision guaranteed by fRCPU hardware leads to high diagnostic coverage for transient faults while the short detection latency (achieved thanks to a dedicated interface between the ARM Cortex-M3 and fRCPU) allows fail operational reactions. There are also special measures on chip to avoid latent faults; for example through built-in self test of supervisor circuits or “scrub and repair” function against bit-flips in memories.
The Toshiba TSB-TC SIL3/ASILD test chip is available now for evaluation by selected partners. It has received Technical Report I from TÜV SÜD for SIL3 functional safety operation. In addition to typical automotive peripheral functions like FlexRayTM and CAN, it offers an operating temperature range of minus 40 to plus 125 degrees Celsius.
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About Toshiba
Toshiba Electronics Europe (TEE) is the European electronic components business of Toshiba Corporation, which is ranked among the world’s largest semiconductor vendors. TEE offers one of the industry's broadest IC and discrete product lines including high-end memory, microcontrollers, ASICs, ASSPs and display products for automotive, multimedia, industrial, telecoms and networking applications. The company also has a wide range of power semiconductor solutions. TEE was formed in 1973 in Neuss, Germany, providing design, manufacturing, marketing and sales and now has headquarters in Düsseldorf, Germany, with subsidiaries in France, Italy, Spain, Sweden and the United Kingdom. TEE employs approximately 300 people in Europe. Company president is Mr. Hitoshi Otsuka.
Toshiba Corporation is a world leader and innovator in pioneering high technology, a diversified manufacturer and marketer of advanced electronic and electrical products spanning information & communications systems; digital consumer products; electronic devices and components; power systems, including nuclear energy; industrial and social infrastructure systems; and home appliances. Founded in 1875, Toshiba today operates a global network of more than 740 companies, with 199,000 employees worldwide and annual sales surpassing US$73 billion.
For more company information visit Toshiba's web site at www.toshiba-components.com
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Toshiba Electronics Europe, Hansaallee 181, D-40549 Düsseldorf, Germany Tel: +49 (0) 211 5296 0 Fax: +49 (0) 211 5296 792197 Web: http://www.toshiba-components.com/pressoffice/index.asp E-mail: MAC/IC:
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Henning Rausch, Toshiba Electronics Europe Tel: +49 (211) 5296 117 E-mail:
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January 2010 Ref. 5937/A