May 7, 2021

ASIL Requirements Drive Memory Evaluations

5 min read
TORONTO—It will be a while before DDR5 dominates the DRAM market, but when it comes...

TORONTO—It will be a while before DDR5 dominates the DRAM market, but when it comes to automotive applications, it makes sense to get a head start to qualify memory devices to meet reliability and functional safety requirements in the latest and greatest automotive systems.

Micron’s LPPDR5 DRAM has already been in production in high volumes for mobile devices. (Courtesy Micron)

Micron Technology recently began sampling its low-power DDR5 DRAM (LPDDR5) memory that is hardware-evaluated to meet the most stringent Automotive Safety Integrity Level (ASIL), ASIL D. It’s one of many companies supplying semiconductor content to the automotive market that seeks external certification or review to meet the requirements of International Organization for Standardization (ISO) 26262 standard that is widely applied automotive systems. The ISO 26262 standard covers automotive functional safety, including advanced-driver assistance system (ADAS) technologies that were once a premium feature, but now prevalent on all new vehicles.

Micron’s LPDDR5 memory is part of a new portfolio of memory and storage products designed for use in different ADAS technologies that might use functional safety-evaluated DRAM, including automatic emergency braking systems, lane departure warning, adaptive cruise control, and blind spot detection systems. All require extremely low latency and reliability, even in a vehicle that’s not fully autonomous. ASIL is a risk classification scheme defined by ISO 26262, and as more electronic devices are integrated into vehicle to enable systems that take great control of vehicles, complying with the spectrum of ASIL classification has become a more frequent requirement.

Functional safety is one reason car makers tend to go with tried-and-true memory devices that already have a strong track record for reliability and longevity required from “automotive grade” components, which are also expected to last 10 years on average in environments ranging from extreme cold to extreme heat. And although LPDDR5 is relatively new, said Robert Bielby, Micron’s senior director for automotive system architecture, it’s already seen large volumes of uptake in mobile devices — billions of units per year, in fact. Whereas automotive will only ingest millions, he said, it will benefit from the learnings in the mobile market.

Micron’s push to meet ASIL-D and ISO 26262 requirements go back a couple of years, said Bielby, and were driven by automotive safety trends. The company has already made significant investments in the automotive market over the past three decades, so it made sense to establish a functional safety office, he said. “Its charter is to really understand what terms and conditions are associated with safety, and what is required as a semiconductor supplier to really be able to deliver qualified safety solutions.” Automotive functional safety requires that design, verification, testing, simulation, and qualifying is done in a manner consistent with the ISO 26262 standard.

The mobile market is by no means the proving ground for ASIL-D qualified LPDDR5, said Bielby, but monitoring the manufacturing of millions and millions of units destined for smartphones enables Micron to tweak processes and production quality to deliver high integrity, high yield and highly qualified products and build on a strong baseline for automotive applications. Ultimately, all Micron customer benefit in some way from the company’s efforts to meet the stringent quality requirements of automotive because the design methodologies are applied across different industry segments.  “It’s not as though automotive is an afterthought, it’s actually a forethought.”

Micron’s LPDDR5 hardware evaluation has also been independently assessed and verified by Exida, which helps a wide variety of companies evaluate and certify systems and components for different industry standards, including automotive. This evaluation helps to speed up the qualification of semiconductor content such as memory for cars, thereby accelerating its adoption.

Even before autonomous vehicles were gaining speed, there was an uptick in semiconductor content in the average car as ADAS worked its way down from being a high-end feature to becoming standard on all vehicles, said Exida CEO Chris O’Brien. As far back as 2005, there was increased adoption of onboard memory for silicon microcontrollers units (MCUs) as geometry sizes shrunk, which meant a requirement to certify its reliability, as memory could become a dominant contributor to the overall safety metrics of the vehicle. “When they couldn’t be just a generic part in the size when the power levels got smaller and the gate sizes got smaller and you could no longer kind of say, ‘Well, you could model that with a generic part’.”

Chris O’Brien

Aside from all the bells and whistles in a modern vehicle cockpit, there’s a lot of systems including breaking and steering that use sensors and are microprocessor-based. For example, a steering system with an MCU means a microcontroller is now in a critical safety path and falls under the umbrella of functional safety standards because they’re using an MCU, software, and communications buses.

Backup cameras, if not full blown ADAS, are becoming a requirement on all vehicles, noted O’Brien, and while not as critical as autonomous driving systems, people are now relying on looking at the dashboard instead of the rear-view mirror, which means not showing the right image or showing a frozen image could lead to an accident.

O’Brien said bigger technology players that provide components to automotive such as Micron and Xilinx have a lot of in-house capabilities, but still require the expertise of an external advisor, as do the large automakers. For the latter, knowing something has already been evaluated by an organization such as Exida allows them to easily adopt and integrate technology with a degree of confidence that it has automotive-grade reliability without doing all the legwork themselves.

ASIL is a risk classification scheme defined by ISO 26262, and as more electronic devices are integrated into vehicle to enable systems that take great control of vehicles, complying with the spectrum of ASIL classification has become a more frequent requirement. (Courtesy Micron) (Click on the image for a larger view.)

Meanwhile, many smaller players are finding there’s opportunity for their products in the rapidly expanding automotive segment and need the certification of an Exida if they are to participate in the market, said O’Brien. “It’s not that they’re not going to be able to come up with really elegant designs. It’s that their organizational maturity could be quite a bit less.”

For automotive, Exida draws on some of its expertise in the industrial segment, which has many of the same functional safety requirements—even low speed robots on a factory floor have the ability to injure someone. “We’ve done recertified chips that have gone into industrial controls, automobiles and collaborative robots,” said O’Brien. In the meantime, Exida is seeing more work related to cybersecurity and artificial intelligence (AI) as they become increasingly adopted into automotive and industrial settings, even if formal standards are still in flux.

Gary Hilson is a general contributing editor with a focus on memory and flash technologies for EE Times.

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