Recently, Tesla announced a recall on certain Model X and S vehicles because of faulty 8 GB embedded multimedia cards (eMMCs) in the microcontroller. The accumulated wear on the eMMC can compromise the main display screen, vehicle alert signals, storage devices, and review cameras. All of these losses add up and deplete the reliability of memory safety operations.  

This recent event illustrates that safety is an essential part of data processing systems and memory in vehicles. 

Double data rate five (DDR5) is one memory technology focused on device-level security. Using dynamic random-access memory (DRAM), DDR5 is said to provide devices with faster data rates, larger bandwidths, and stronger performance. Typically we only hear buzz around DDR5 being used in mobile devices and CPUs, but DDR5 is versatile enough to operate in automotive applications as well.

ASIL-rated systems and functions

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ASIL-rated systems and functions. Image used courtesy of Micron
 

Introducing DDR5 into automotive systems brings a rise in memory, processing, reliability, and performance while increasing safety capabilities. Micron recently emphasized this point with the “industry’s first automotive low-power DDR5 DRAM (LPDDR5) memory” that meets key hardware-focused automotive safety standards.

Levels of DRAM: Standard, Graphics, and Automotive

Before delving into the intersections between automotive memory and hardware security, it may be useful to first outline the three levels of DRAM: standard DDR, graphics DDR, and mobile DDR.

Standard DDR targets servers, cloud computing, and networking by allowing wider channel widths, higher densities, and different form-factors. Current DDR4 provides data-rates of up to 3200 Mbps, but once DDR5 rolls in, it is expected to reach 6400 Mbps in bandwidth speeds. 

Flow chart showcasing DRAM being broken down per market

Flow chart showcasing DRAM being broken down per market. Image used courtesy of Synopsys

The next category of DDR is the graphics DDR (GDDR), which targets data-intensive applications requiring a very high throughput, such as graphics-related applications and data center acceleration. Switching to any graphics-based DDR5 can enable full high-definition video files of 3.7 GB/s.

Finally, low-power mobile DDR (LPDDR) targets mobile and automotive applications. LPDDR offers narrow channel-widths and several low-power operating abilities. Current LPDDR4 and LPDDR4X run the mobile market and can support data rates up to 4267 Mbps and will similarly upgrade to 6400 Mbps during the switch DDR5.  

Error Correction Codes From DDR4 to DDR5

One important consideration for secure automotive memory is error correction codes (ECC), a critical automotive protocol that self detects and retrieves data errors transferred through the embedded hardware. According to SK hynix, ECC is a key factor in automotive memory because it can prevent system faults while providing a smooth autonomous driving experience. 

The LPDDR4 is capable of transmitting data arrays of 128 bits with 8 bits being retrieved for the ECC. In contrast, LPDDR5 is projected to have a 16 GB DRAM to support a data transfer rate of 5.2 GB/s, which will be nearly 60% faster than its predecessor.

Comparison of different generations of LPDDR

Comparison of different generations of LPDDR. Image used courtesy of Utmel Electronic
 

While this level of security and speed is an appealing feature in memory devices, designers should consider other design characteristics of DDR5. For instance, DDR5 has a lower operating voltage, VDD, which means a smaller margin for noise immunity. Aside from that, designers will have more flexibility with complex automotive designs since separate power management is present in DDR5-embedded ICs.

Micron’s New LPDDR5 and ASIL Classifications 

Micron recently released a new portfolio of memory and storage devices that aim for automotive safety. Micron’s most recent announcement of new LPDDR5 memory touts that the device is Automotive Safety Integrity Level (ASIL) qualified—to ASIL D, specifically.

ASIL is a risk classification defined by ISO 26262, the international safety standard for electrical components in automotive systems. ISO 26262 compliance entails that a vehicle is held to the highest safety functionality standard in the game, which is increasingly important with ADAS.

ASIL breaks safety levels into a few categories: 

  • ASIL B: Brake lights, rearview cameras, headlights
  • ASIL C: Active suspension, radar cruise control
  • ASIL D: Antilock braking, electric power steering, airbags, engine management 

ASIL's failure metrics for hardware components

ASIL’s failure metrics for hardware components. Image used courtesy of Micron
 

Safer LPDDR5 Can Address Systemic and Hardware Faults

To meet top-level safety requirements, LPDDR5 typically incorporates safety mechanisms that detect and control memory errors during operation. 

Micron breaks down security risks in automotive memory into two categories: systematic and hardware faults. Systematic faults are addressed by the memory’s ECC, detecting errors that are sorted out during data transmission. Hardware faults must be addressed during the testing and manufacturing phases. 

Safety is a priority for all vehicles, but especially in those with autonomous systems. With DDR5 entering the automotive market, various sensors, controllers, switches, and gates will thrive as they simultaneously operate and transfer data at faster—and safer—rates than before.

This post was first published on: All About Circuits

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