IEEE Consumer Electronics Magazine - September 2018 - 13

the mirror size, and external magnets are required. The less
pursued piezoelectric actuation [Figure 5(c)] [18] promises
large torques at reasonable voltage levels. Its drawbacks are
the complex kinematics needed to amplify the modest deformations of piezoelectric materials and the MEMS integration
of a piezoelectric device. The latter is on its way to being
solved since piezoelectrics is an enabling technology for
other applications. Today, it is far from clear which is the
technical path to success for automotive lidars. What seems
likely is that the requirements of small size, high performance, and mass-market-compatible costs will force a path
that goes through the development of MEMS micromirrors.

NVM for Automotive Applications

In-Vehicle
Embedded Systems

HIGHLY RELIABLE NVM FOR
AUTOMOTIVE ELECTRONICS

Data Storage

Code
Storage

NAND Flash
Memories

NOR Flash

NOR Flash
EEPROM

SD Cards
eMMC
Solid-State
Drives

Nonflash NVM (e.g., PCM,
TAS-MRAM, MEMS-Based)

AUTOMOTIVE APPLICATIONS OF NVM

100 million
10 million

NVM for Assisted-Driving
Scenario or Safety Applications

108
107

1 million
100,000
10,000

106
105

1,000
100
10
1

103
102
101

104

1995 2000 2005 2010 2015 2020
Year

100

Computational Power (MIPS)

FIGURE 6. The taxonomy of NVM integrated in the automotive
environment. EEPROM: electrically erasable programmable readonly memories; PCM: phase-change memories; TAS: thermally assisted switching; MRAM: magnetic random access memory; eMMC:
embedded multimedia card.

NVM Size (Bytes)

NVMs in the automotive field (Figure 6) are used mainly for
infotainment or onboard control/data-processing systems.
Concerning the data storage for infotainment, the choice is
typically NAND flash. This mature consumer NVM technology has a very high storage density (in the terabits domain)
with a very low cost per bit, easily achievable by implementing the multibits-per-cell storage paradigm [19]. This solution is favored for mass-storage applications where a high
amount of data need to be stored, often trading with the
poor write/read access performance and the inherent reliability of the media. The preferred format for frequent userdata exchange is the secure digital (SD) card (or its variants
miniSD and microSD), which integrates a controller for
protocol interfacing and memory management functions
with a NAND flash memory module. The media removability feature is a great benefit since it allows off-vehicle data
updating. This NVM technology can be easily integrated,
along with a dedicated memory controller, to form complex
storage systems like solid-state drives. The reliability constraints for this memory technology are the same as for any
consumer application embodying a NAND flash since no
hostile operating conditions are foreseen in terms of operating temperature, voltages, and other electrical concerns.
From the qualifications and reliability standpoint, those
memories feature a limited lifetime (a few years), especially
for multibits products with the capability to retain the information of a few months (i.e., three months at a 40 °C storage temperature).
Concerning an onboard NVM-embedded systems scenario, there are two main applications: data and code storage.
The data storage class is intended for sensor calibration,
V2X, or simple data logging activities in the car that do not
require an excessive amount of data. The code storage class is
for real-time operating systems executing heavy computation
algorithms or for sensor/actuator control codes execution. In
both cases, there is no need for mass-storage platforms;
therefore, all of these NVMs should have a storage density
ranging from a few kilobytes up to some megabytes. The
increase of the number of sensors integrated in the car as well

Infotainment

Memory Size
MCU Computational Power
FIGURE 7. The trend of embedded NVM size compared to the
required computational power for assisted-driving or active safety
automotive applications [20].

as the number of functionalities requiring MCUs with larger
word size (from 8 up to 64 bits) will in a nearby future, call
for a storage-density increase.
Figure 7 shows the trend relationship between the NVM
size and the computational power in a million instructions per
second (MIPS) for automotive embedded MCUs [20]. Both
parameters are expected to increase at the same pace in the
next years, reaching tens of megabytes in NVM size for a corresponding computational power of a few kilo-MIPSs in 2020.
Figure 7 refers to assisted driving and active safety applications that are far from autonomous driving [21] requirements,
for which the NVM reliability comes to be at the forefront.
september 2018

IEEE Consumer Electronics Magazine

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