Semiconductor manufacturers, including memory suppliers, are providing strong support for functional safety efforts by Tier 1 automotive suppliers and OEMs. Last November, Micron released a video, "Consulting Memory Suppliers on DRAM Functional Safety," in which we pointed out that memory is playing an increasingly important role in influencing overall safety levels and outlined issues to consider when developing safety strategies.
ISO 26262 defines functional safety as "eliminating unreasonable risks arising from the faulty behavior of electrical/electronic systems." Faults are classified into two types:
• Systematic failures: These are failures that occur in a deterministic manner and typically arise during product design or development. These failures are generally addressed using documented processes and methods, including safety planning, safety concept documents, requirements traceability, proactive safety analysis tools, reliability verification, operating procedures, and other relevant factors.
• Random failures: These are failures that occur randomly during the lifespan of a device. Random failures can be further divided into two categories: transient failures (single-event disturbances or soft errors) and permanent failures (hard errors, such as being stuck at the logic level). These types of failures are generally addressed by introducing safety mechanisms. These mechanisms help detect these failures and enable the system to take appropriate measures, including correcting the failure or keeping the system in a safe state.
Several security mechanisms are employed at the hardware and system levels, including:
• Redundancy: This mechanism can typically be implemented at the hardware level. • Cyclic Redundancy Check (CRC): This mechanism is typically used to detect errors.
• Error correction codes: This mechanism is generally used for error detection and correction.
• Built-in self-test: This mechanism provides additional circuitry to continuously or during power-on testing to verify that the device is operating correctly.
The effectiveness of safety mechanisms used to detect random failure times (FITs) and the likelihood of risk occurrence is typically measured using metrics such as Single Point of Failure Metric (SPFM) and Potential Failure Metric (LFM). These metrics are used to measure the functional safety of a given hardware component.
ASIL has established safety requirements for automotive components.
ASIL stands for Automotive Safety Integrity Level, a risk classification system defined by the ISO 26262 standard for the functional safety of road vehicles. ASIL A is the lowest safety level, while ASIL D is the most stringent. Higher ASIL levels typically imply increased cost and complexity; therefore, the required ASIL level for a given system is directly related to the impact of system failures on vehicle operation.
For hardware components, ASIL requires that necessary values for failure indicators be defined, as shown in the table below.
Micron introduces industry-leading series of automotive safety-compliant solutions
Based on a deep understanding of the automotive market and its crucial role in safety applications, Micron recently launched an industry-leading suite of safety-based solutions. These solutions underscore Micron's 30-year commitment to providing leading solutions to the automotive market and reflect the company's extensive investments over the past two years across various sectors to meet evolving demands for safety and compliance solutions.
• Establish a functional safety-focused department composed of senior safety professionals from the industry.
• Fully adopt processes and methods compliant with ISO 26262 standards.
• A team of security experts, including system architects and application engineers, was established to provide consulting support.
• According to an independent assessment conducted for the first time by industry-leading safety experts exida, Micron's automotive LPDDR5 meets ASIL D and higher safety system requirements.
• In accordance with Clause 13 of ISO 26262-8, a hardware evaluation report was obtained from the supplier.
• Extensive functional safety and incidental analyses greatly simplify customer analysis.
JEDEC-compliant LPDDR5 is the first in Micron's broad portfolio of automotive memory and storage products, suitable for any ASIL-level safety system. System integrators are ultimately responsible for verifying the suitability of all electronic components and subsystems for safety-related systems; as a memory developer, Micron possesses the expertise and design data to support system integrators in this verification process. Micron's LPDDR5 products come with product safety documentation, including the industry's first supplier-provided hardware evaluation report, as well as safety application notes and analysis reports. Furthermore, the safety-compliant LPDDR5 memory series incorporates a unique and innovative "Safety Engine," offering significant advantages in system-level performance, power consumption, performance, and cost. Micron's safety solutions enable system integrators to better ensure DRAM is unaffected by system failures, while delivering significant improvements in system performance, power consumption, cost, and availability.
Micron's ability to launch this innovative product line is based on a deep and comprehensive understanding of DRAM, the automotive market, related architectures, and functional safety. The first automotive-safety compliant packages are now available, and the products are in mass production at our manufacturing facilities.
Alexander Griessing, COO and Chief Safety Officer of exida, a leading independent functional safety specialist, points out: “Functional safety is a critical part of the development of advanced automotive systems, but until now, memory has been somewhat neglected, treated merely as a ready-to-use product. Micron’s launch of industry-leading automotive LPDDR5, precisely compliant with the ISO 26262 standard, sets a new benchmark for the memory industry. Increased focus on functional safety will benefit all parties, including automakers and consumers who need advanced, safe vehicles.”
