Passive Components Enable V2X and 48V Automotive Systems Vital to Addressing Evolving Safety and Fuel Efficiency Demands

James Emerick, Field Application Engineer, KYOCERA AVX


Consumer and regulatory demands for safety and fuel efficiency improvements are driving continued evolution in the automotive industry

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Figure 1: Standard DSRC V2X infrastructure

­Automotive safety has always been a top priority for both consumers and regulatory bodies, but the growing availability of advanced driver assistance systems (ADAS) and the increasing viability of driverless technologies requires innovative approaches to this age-old requirement. Similarly, while fuel efficiency has long been critical to consumers, new regulatory requirements aimed at reducing CO2 emissions are challenging automotive manufacturers to make even more drastic and impactful improvements.

Two current trends in the automotive industry offer prime examples of how manufacturers are responding to these new safety and fuel efficiency demands. The integration of vehicle-to-everything (V2X) communication technologies is expanding the very definition of automotive safety, extending it well beyond the vehicle itself and out into the world around it, and the growing popularity of 48V subsystems is giving automotive manufacturers a definitive way to satisfy challenging fuel efficiency demands. While these two trends may well seem unrelated on the surface, both are enabled by new classes of passive components engineered to deliver new capabilities, high reliability, and peak performance and satisfy strict automotive regulatory requirements.

V2X Communications Systems

V2X communications systems were first introduced back in 1999, when the bandwidth was initially allocated, and allow vehicles to communicate with other vehicles (V2V communications), with infrastructure (V2I communications), and with pedestrians (V2P communications). These communication capabilities, collectively known as vehicle-to-everything (V2X) communications technologies, straddle the regulatory domains of several different governing bodies in the United States, including the Department of Transportation (DOT), the National Highway Traffic Safety Administration (NHTSA), and the Federal CommunicationsCommission (FCC) — all of which aim toimprove driver, passenger, and pedestrian safety as well as energy efficiency by reducing accidents via traffic monitoring and control.

For example, V2V automotive systems can alert drivers about impending forward collisions, indicate when blind spots are occupied, and issue “do not pass” warnings to improve drivers’ awareness and mitigate collisions. V2I technologies integratepublic infrastructure into automotive communication systems and can allow emergency response and public transit vehicles to communicate with traffic lights to enabling priority access. They can also notify heavy commercial vehicles and freight transport vehicles about the status of upcoming traffic signals to minimize braking and improve energy efficiency and can accurately predict and reliably capture red light violations.

However, while these impactful communication technologies have been tested and proven and even introduced to market, they haven’t yet lived up to their potential because V2X communications systems rely on a combination of standardization and broad adoption that has yet to be achieved. One of the primary reasons behind this obstruction is that the V2X access layer quickly diverged into two competing camps — the dedicated short-range communications (DSRC) strategy based on the IEEE 802.11p standard and WLAN technologies and the cellular-based V2X protocol (C-V2X) based on LTE and 5G standards and technologies — which has led to serious issues with FCC spectrum allocation and significantly delayed the finalization of a standard.

The basic V2X structure is shown in Figure 1 and is the serves as the basis for existing DSRC solutions. In this structure, vehicles primarily communicate directly with the internet and each other using a network of roadside units.

The C-V2X structure (pictured in Figure 2), on the other hand, relies entirely on cellular communications between the various objects in the network. Proponents of the C-V2X structure cite the fact that it eases integration with existing infrastructure and will become even more robust as more 5G networks are deployed — which will provide direct benefits for V2I systems, including the ability to accurately predict and capture red light violations, amongst other safety infractions — as primary reasons to standardize this C-V2X over DSRC.

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Figure 2: Standard C-V2X infrastructure. (Imagecourtesy of TelecomTV.)


DSRC V2X technology has been in production since 2015 and equipment has already been deployed in the United States and Japan. But since then, the Chinese government has launched and completed a comprehensive series of C-V2X pilot programs and capacity tests in cooperation with more than 100 leading global automotive and technology companies, including Ford, Qualcomm, and Autotalks.

China currently has the most 5G networks in the world. By late 2021, China had more than 1.39 million operational 5G base stations, more than 2,300 hybrid and virtual private 5G networks, and more than 1,800 active 5G construction projects. In terms of coverage, that means that each of China’s 299 prefecture-level cities, at least 97% of its 1,355 counties, and roughly 40% of its many townships — or approximately 450 million people — already had 5G coverage by the end of last year. As a result, China’s series of Internet of Vehicles (IoV) projects, including its many C-V2X capacity tests and interoperability demonstrations, have successfully demonstrated technology readiness and industry maturity and are rapidly accelerating the commercialization and cross-platform interconnectivity of IoV and C-V2X technologies. In response, OEMs are rushing to mass produce a slate of vehicular 5G technologies to satisfy projected sales of 3.68 million units by 2025.

Europe conducted similar tests around the same time and, in February 2020, the European Telecommunication Standardization Institution (ETSI) even published the first release of its “Intelligent Transport System (ITS); Cooperative ITS (C-ITS)” standard, which defines C-V2X as an approved access layer for intelligent transportation systems. However, Europe had already defined DSRC WiFi as the V2X standard in May of 2019 and, although 5G vendors revolted, the U.K. still only had 57 cities with active 5G networks as of May 2022 versus China’s 356 and the United States’ 296. So, both technologies are still vying for regional superiority and, as such, stymying the widespread standardization and adoption of V2X communications systems, which is also happening in the U.S. and Japan.

Given the prevalence of such obstacles combined with the growing global interest in V2X communication systems, Autotalks prudently incorporated C-V2X and DSRC layers into its automotive qualified AEC-Q100 grade 2 chipsets to continue accelerating the automotive industry’s adoption of V2X technologies while the regulatory dust settles.

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Figure 3: This block-level STMicroelectronics V2X communications system diagram represents the typical structure of a V2X system and features Autotalks’ global V2X solutions. (Image courtesy of STMicroelectronics)


The various in-vehicle network, infotainment, and safety subsystems in V2X communications systems are generating greater demand for high-quality, automotive-grade passive components. Depending on the system’s complexity and required features, these can include passive antennas for 5.9GHz cellular, 2.4GHz and 5.0GHz Wi-Fi, and 2.4GHz Bluetooth as well as dual- and tri-band and GNSS antennas. Other passive components vital to V2X communications systems’ analog- and RF-centric applications include AEC-Q200-qualified ceramic, feedthrough, and polymer capacitorswith high-voltage, high-CV, and high-temperature capabilities and multilayer varistorswith low parallel inductance and high current and energy handling, multiple strike, and EMI/RFI capabilities.

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Figure 4: KYOCERA AVX designs and manufactures a wide range of advanced passive components qualified to AEC-Q200 and optimized for use in V2X applications, including embedded, stamped-metal, dual-dand WiFi/Bluetooth antennas (top left), V2X ceramic patch antennas (bottom left), high-voltage SMT MLCCs (top center), feedthrough capacitors (bottom center), high-temperature, low-capacitance varistors (top right), and TCO Series polymer capacitors (bottom right)


48V Electrical Systems

Several global regulatory agencies have set targets aimed at improving fuel efficiency, reducing greenhouse gas emissions, and encouraging eco-innovation by offering emission reduction creditsfor new technologies that reduce CO2 emissions. For instance, in the United States, the Environmental Protection Agency (EPA) and the NHTSA adopted the Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule, which mandates an annual 1.5% increase in fuel economy and carbon dioxide stringency standards for all 2021–2026 model-year vehicles.

One of the surest ways to meet these aggressive targets is to augment internal combustion engines with hybrid electric technologies that minimize the amount of mechanical power that auxiliary systems like AC compressors and brake vacuum pumps draw from the engine. Traditional 12V power supplies are not equipped to handle the power demands associated with the steady proliferation of automotive electronics systems ranging from sensors and computers to comfort control and infotainments systems. So, the automotive industry is experiencing a widespread shift to 48V power supplies capable of providing four times the available power without incurring additional wiring and connector losses. However, given that the automotive industry has utilized traditional 12V power supplies since its inception, the shift to 48V systems is no simple feat. As such, early approaches are employing a hybrid 12V/48V power supply approach.

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Figure 5: A diagram of a simple 12V/48V dual-voltage battery management (2VBM) system


In hybrid or dual-voltage battery management (2VBM) automotive systems, the traditional 12V system drives the electronic control unit (ECU) and other legacy systems and communicates with the 48V system, which is used to power components like high-power MOSFETs that drive brushless DC motors.

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Figure 6: A detailed 48V automotive system schematic courtesy of Texas Instruments


To achieve even greater fuel efficiency, many automotive manufacturers are taking hybrid 2VBM automotive systems a step further by replacing vehicles’ traditional starter motor with a motor-generator capable of recapturing energy during braking, or even installing a more powerful electric motor capable of replacing its internal combustion engine at low speeds.

These system-level changes also require component-level changes. For example, 12V and 48V batteries require temperature monitoring solutions, like thermistors, to identify and alert users about potential damage to individual battery cells. Thermistors are popular solutions for temperature sensing and temperature compensation applications in high-reliability automotive and industrial applications and are available in with leaded, leadless, and surface-mount form factors with standard and high precision, multiple stability options, a wide resistance range, and AEC-Q200 qualification. Similarly, regenerative braking applications often require a combination of primary or secondary batters and supercapacitors with very high capacitance and very low ESR to deliver instantaneous power pulses as needed. In addition, since regenerative braking systems often experience high voltage transients, they frequently employ advanced passive components in their control circuits, including multilayer ceramic, niobium, and polymer capacitors capable of reducing voltage pulsation and multilayer varistors capable of decoupling high di/dt and providing transient voltage protection and EMI attenuation.

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Figure 7: KYOCERA AVX designs and manufactures a wide range of advanced automotive-qualified passive components, including high-precision, resistance-accurate leaded and leadless thermistors(top left), leaded disc thermistors(top center), leadless disc thermistors(top right), surface-mount thermistors(bottom left), SCC Series supercapacitors(bottom center), and TransFeed Automotive Series varistors (bottom right)


As consumer and regulatory demands for automotive safety and fuel efficiency improvements continue to inspire new applications like ADAS, V2X communications systems, and 48V subsystems, vehicle manufacturers will have to incorporate new classes of passive components engineered to deliver new capabilities, high reliability, and peak performance and satisfy strict automotive regulatory requirements. Partnering with proven passive component suppliers like KYOCERA AVX can help OEMs achieve their innovative design goals while also meeting the automotive industry’s challenging cost constraints.