MCU integration to increase as EV architecture evolves – An interview with STMicroelectronics (part 1)

The growing trend in vehicle E/E architecture is to move from distributed to centralized designs. As part of this evolution, STMicroelectronics recently announced the start of volume production of its Stellar P platform, which is capable of integrating all powertrain controlling functions, such as the inverter, onboard charger (OBC), DC/DC converter, and battery management system (BMS).

To see the second part of the interview with STMicroelectronics: Automotive Innovation and Supply Chain Resilience (Part 2).

The COVID-19 pandemic drove MCU prices to double-digit growth for several years due to a number of factors, including supply chain disruptions, shipping disruptions, workforce shortages, fab capacity allocation misjudgments, and new product allocations.

It has been a common misconception that pricing will return to “normal” now that the pandemic is over. On the contrary, Yole Group’s analysts have seen average prices continue to rise and peak around the end of 2023 into early 2024, and they believe “normal” will remain much higher than pre-pandemic prices, owing to global inflation as well as strong growth in product substitutions of higher-performance products and more demanding applications (Source: Status of the Microcontroller Industry report).

One way for OEMs to optimize their semiconductor supply is for each MCU to be used in multiple ways to perform numerous functions requiring more powerful resources. Yole Group’s analysts see the vehicle architecture evolving at different rates toward a layered intelligence approach, with intelligence in tightly coupled controllers still in edge control units, zones of control, or, at the top, domain controllers.

Yu Yang, Principal Technology & Market Analyst specializing in automotive semiconductors at Yole Group, and Tom Hackenberg, Principal Analyst for Computing and Software in the Semiconductor, Memory and Computing Division at Yole Group, recently spoke with Davide Santo, Automotive MCUs Director, and Francesca Canali, Marketing Manager, Automotive Processors, at STMicroelectronics in a wide-ranging conversation.

Together, they discussed STMicroelectronics’ strategy for the new Stellar platform, the growing trend towards centralization of EV architecture, and the competition emerging from China.

Welcome to 2025! At Yole Group, we’re entering the new year with great anticipation and excitement. The world of semiconductor technologies, particularly in the realm of automotive applications, holds incredible promise. The analysts foresee remarkable challenges and opportunities shaping the industry this year. Let’s dive into these insights with the first edition of Yole Group’s Industry Insights interview series with STMicroelectronics.

Enjoy this conversation!

Yu Yang (YY): We are seeing a trend towards a more centralized architecture, including STMicroelectronics launching the next-generation Stellar P platform, which will integrate different powertrains and include some of the chassis and thermal management functions. Will this continue in the coming years?

Davide Santo (DS): We have recently launched new components of our Stellar family, designed to address a wide range of automotive applications across multiple segments. These MCUs go beyond body powertrains and chassis applications, offering advanced integration of functions with flexible safety support, reflecting the trend toward “zonalization” in vehicle architecture. The first Stellar MCUs have entered production, supporting key industry shifts, such as advanced powertrain integration and the transition to electrification. They are also ready to support upcoming regulatory demands, such as Euro 7 in Europe. Beyond powertrain and electrification, the Stellar series continues to enable the integration of body and advanced gateway functions supporting the evolving connectivity needs of modern vehicles.

At STMicroelectronics, we believe the trend that is being called X-in-1 in China is one of the major trends that are emerging in electrification for practical reasons. It reduces the number of ECUs, streamlines vehicle architecture, and highlights one of the strengths of the Chinese vendors – their exceptional speed of execution.

This trend is accelerating, and the number of functions integrated is increasing rapidly from the initial three – we have already encountered applications from some of our customers that integrate up to 10 different functions. This evolution entails some challenges at the software and hardware level, such as protection of software tasks, isolation, and maintaining deterministic performance, all of which our architecture is designed to address. We see this shift coming very fast – it’s not going to be in 10 years, it’s going to be within two years.

In China, we have seen the progression to 6-in-1 and even to a record 11- or 12-in-1 integration. However, these high-integration solutions are more suitable for smaller cars with lower power needs and less of a problem with EMI and thermal management. Larger and more powerful vehicles with bigger motors will likely stay longer with 3-in-1, gradually integrating more functions, including OBC and DC-DC.

YY: If that is the case, do you have other solutions for that? Or is the current MCU good enough for that purpose?

DS: One of the factors that we took into consideration when we designed and introduced the Stellar platform is scalability. For the simpler cases, the 3-in-1 offers a balanced level of integration without being too ambitious. Stellar MCU is designed with flexibility in mind, enabling customers to select the desired performance level. Additionally, it allows split lock – maintaining lockstep core configurations depending on the required safety level.

The second characteristic is the ability to leverage memory effectively. The high density of our PCM (Phase Change Memory) allows us to have a great level of memory flexibility.

Furthermore, the platform offers a high number of I/Os, giving developers the flexibility to achieve greater integration. All of these features – scalable performance, efficient memory utilization, large I/O number – are embodied in the Stellar series P and G, with even more enhancements planned for future series.  Combined with its strong ecosystem, the Stellar MCU is well-positioned to support and accelerate these emerging trends.

Francesca Canali (FC): In July, the number of electric vehicles sold in China exceeded the number of ICE vehicles, a milestone that highlights the EV market’s rapid growth. The majority of these sales are concentrated in the mid-to low-end segment, largely due to factors like affordability and range limitations. While the high-end market remains smaller for now, we are preparing for its future expansion by ensuring full scalability in our solutions. When looking at the different geographies, a key question remains: will this mid-to low-end trend gain traction in other regions outside China and Asia? Can regional differences shape the pace and adoption of the X-in-1 trend elsewhere?

Simultaneous with the X-in-1 trend, Yole Group’s analysts are seeing a reduction in the number of microcontrollers: previously, each system had a controller, but now they’re merging into one controller. The price of an MCU is increasing though its performance has increased much more compared to the previous generation.

YY: How do you view this trend, including an overall vehicle E/E architecture, not only the powertrain?

DS: The number of ECUs is reducing, while the number of microcontrollers that can be used or the complexity of microcontrollers is increasing. This level of integration brings complexity and challenges because we are pushed as a manufacturer, into technology nodes that are more aggressive, while simultaneously, the computational complexity requires more sophisticated device architectures.

There is a clear difference between the approaches of Silicon Valley and China in tackling automotive integration. In Silicon Valley, the focus lies on optimizing functions, distributing software efficiently, and leveraging Ethernet-based communication networks. China embraces the X-in-1 approach, which forces the coexistence of different applications within a single system. This is made possible by highly integrated silicon microcontrollers and advanced software capabilities. While the X-in-1 emphasizes integration, it does not prioritize function optimization as Silicon Valley does. Despite these differences, both approaches ultimately aim to reduce the number of ECUs and lower the cost of vehicle digitalization.

As the market evolves, price and performance will reflect these strategies. Advanced designs will incorporate sophisticated switching capabilities, high-performing cores, and the capability to communicate rapidly both between cores and externally, all while reducing power consumption. This will drive the next phase of development in automotive MCUs.

The automotive MCU market is dominated by 40 nm technologies with an average memory size of 4MB, expected to double to 8MB in the next five years due to integration demands. The transition to 28 nm and smaller geometries will bring a leap in performance, not just in the frequency of the cores, but also in the capability to address latency, ensure determinism, and optimize memory utilization. Dense NVM and SRAM will play a crucial role. Whoever can best integrate SRAM with NVM will make the best-balanced solution. Ultimately, the most successful chip will be the best balance of performance, efficiency, and integration. As history has shown, the market-leading chip is rarely the one with the highest absolute performance but rather the one that is best balanced for the demands of the industry.

STMicroelectronics recently announced a roadmap for microcontrollers targeting automotive that includes the STM32. This seems to indicate that you believe that rather than all of the functions going into the domain controller, there will be a layer of functions from the domain controller down to several STM32 ASIL-B-compliant microcontrollers surrounding the domain controllers.

Tom Hackenberg (TH): Can you comment on that?

DS: STM32 will be in automotive, and this is a great step. There are multiple reasons for that. First of all, we have established a leadership position in STM32 with 1.2 million active developers in our ecosystem in 2024, and its ease of adoption is an essential factor for the future.

Second, not all functionalities will be aggregated into a domain, multiple domain, or zone controllers. A significant portion of the market remains with smaller microcontrollers that are essential for specific applications, and we are serving them with an STM32-type of architecture. These ARM-based microcontrollers support functional safety and will be a cornerstone of our offering.

We will also gradually harmonize security features across platforms, delivering STM32 versions and adopting HSM-based security capabilities as in the Stellar MCUs. Our vision is to create a unified platform that leverages shared technologies, the same memory type, and scalable performance through ARM-based computational capability and ecosystems, all while maintaining scalability within product series.

Coming back to the question of the layered approach. There’s a clear trend toward function aggregation in applications with non-volatile memory sizes ranging from 2-4MB up to 32MB and scalable multi-core architectures.

On the other hand, STM32 for automotive, which we call the STM32A, will offer a strong choice for single application use cases due to its cost-effectiveness, simple design, and large ecosystem.

At the same time, we are advancing efforts to unify our platforms across the broad spectrum of application needs. In the long term, our goal is to provide cohesive hardware and ecosystems capable of addressing solutions that scale from small, sub-1MB parts to over 32MB. Tools like STM32Cube, widely used for STM32 microcontrollers, will expand to support all of ST’s ARM-based automotive products, offering developers a streamlined environment for projects of all sizes and complexities.

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As well as the Automotive Teardown Tracks.

Source: st.com

To see the second part of the interview with STMicroelectronics: Automotive Innovation and Supply Chain Resilience (Part 2).