In-depth analysis of automotive control chips (MCU)

Latest update time：2024-10-10

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Control chips mainly refer to MCU (Microcontroller Unit) , that is, microcontroller, also known as single-chip microcomputer, which appropriately reduces the CPU's main frequency and specifications, and integrates multiple functional modules and interfaces such as memory, timer, A/D conversion, clock, I/O port and serial communication on a single chip to realize terminal control functions. It has the advantages of high performance, low power consumption, programmability and high flexibility.

Automotive-grade MCU schematic

※Source: Public information, provided by the compilation unit

Automobiles are a very important application field for MCUs. According to IC Insights data, the proportion of global MCUs used in automotive electronics in 2019 was about 33%. The number of MCUs used in each high-end car is close to 100. From the on-board computer, LCD instrument panel, to the engine and chassis, all large and small components in the car need to be controlled by MCU. In the early days, 8-bit and 16-bit MCUs were mainly used in automobiles, but with the continuous strengthening of automobile electronics and intelligence, the number and quality of MCUs required are also constantly improving. At present, the proportion of 32-bit MCUs in automotive MCUs has reached about 60%, among which ARM's Cortex series cores are the mainstream choice of various automotive MCU manufacturers due to their low cost and excellent power consumption control.

The main parameters of automotive MCU include operating voltage, operating main frequency, Flash and RAM capacity, number of timer modules and channels, number of ADC modules and channels, type and number of serial communication interfaces, number of input and output I/O ports, operating temperature, packaging type and functional safety level, etc.

According to the number of CPU bits, automotive MCUs can be mainly divided into 8-bit, 16-bit and 32-bit. With the upgrading of technology, the cost of 32-bit MCUs has continued to decline, and it has now become the mainstream, gradually replacing the applications and markets previously dominated by 8/16-bit MCUs.

If divided by application field, automotive MCU can be divided into body domain, power domain, chassis domain, cockpit domain and intelligent driving domain. For the cockpit domain and intelligent driving domain, the MCU needs to have higher computing power and high-speed external communication interfaces, such as CAN FD and Ethernet. The body domain also requires a large number of external communication interfaces, but the computing power requirements for the MCU are relatively low, while the power domain and chassis domain require higher operating temperature and functional safety level.

Chassis domain control chip

The chassis domain is related to the driving of the car. It is composed of the transmission system, driving system, steering system and braking system. It consists of five major subsystems, namely steering, braking, shifting, throttle and suspension systems. With the development of intelligent automobiles, the perception and recognition, decision-making planning, and control execution of smart cars are the core systems of the chassis domain. Wire-controlled steering and wire-controlled braking are core components for the execution end of autonomous driving.

(1) Work requirements

The chassis domain ECU adopts a high-performance, upgradeable functional safety platform and supports sensor clusters and multi-axis inertial sensors. Based on this application scenario, the following requirements are put forward for the chassis domain MCU:

High main frequency and high computing power requirements, the main frequency is not less than 200MHz and the computing power is not less than 300DMIPS

The Flash storage space is not less than 2MB, with code Flash and data Flash physical partitions;

· RAM no less than 512KB;

High functional safety level requirements, can reach ASIL-D level;

Support 12-bit precision ADC;

Support 32-bit high-precision, high-synchronization timer;

Support multi-channel CAN-FD;

Support no less than 100M Ethernet;

Reliability no less than AEC-Q100 Grade1;

Support online upgrade (OTA) ;

Support firmware verification function (national secret algorithm) ;

(2) Performance requirements

Kernel part:

I. Core main frequency: the clock frequency of the core when it is working, which is used to indicate the oscillation speed of the core digital pulse signal. The main frequency cannot directly represent the core's computing speed. The core's computing speed is also related to the core's pipeline, cache, instruction set, etc.

II. Computing power: DMIPS can usually be used for evaluation. DMIPS refers to a unit that measures the relative performance of the MCU when testing the comprehensive benchmark program.

Memory parameters:

I. Code memory: memory used to store code;

II. Data storage: a memory used to store data;

III.RAM: Memory used to store temporary data and code.

Communication bus : including vehicle-specific bus and conventional communication bus;

High - precision peripherals;

Operating temperature ;

(3) Industrial structure

Since different car manufacturers use different electronic and electrical architectures, the demand for chassis domain components will be different. Different models of the same car manufacturer have different ECU choices for the chassis domain due to different high and low configurations. These distinctions will cause the demand for chassis domain MCUs to be different. For example, the Honda Accord uses 3 chassis domain MCU chips, and the Audi Q7 uses about 11 chassis domain MCU chips. In 2021, the production of Chinese-branded passenger cars will be about 10 million, of which the average demand for chassis domain MCUs per vehicle is 5, and the total market volume will reach about 50 million. The main suppliers of MCUs in the entire chassis domain are Infineon, NXP, Renesas, Microchip, TI and ST. These five international semiconductor manufacturers account for more than 99% of the market share of chassis domain MCUs.

(4) Industry barriers

From the perspective of key technologies, chassis domain components such as EPS, EPB, and ESC are closely related to the driver's life safety, so the functional safety level requirements for chassis domain MCUs are very high, basically ASIL-D level requirements. There is no MCU with this functional safety level in China. In addition to the functional safety level, the application scenarios of chassis domain components have very high requirements for the MCU's main frequency, computing power, memory capacity, peripheral performance, and peripheral accuracy. Chassis domain MCUs have formed very high industry barriers, which need to be challenged and broken by domestic MCU manufacturers.

In terms of the supply chain, since chassis domain components require control chips with high main frequency and high computing power, this places relatively high demands on the process and manufacturing process of wafer production. At present, it seems that at least 55nm or higher processes are required to meet the MCU main frequency requirements of more than 200MHz. In this regard, the domestic automotive MCU production line is not yet complete and has not reached the mass production level. International semiconductor manufacturers basically adopt the IDM model. In terms of wafer foundries, currently only TSMC, UMC and GlobalFoundries have the corresponding capabilities. Domestic chip manufacturers are all Fabless companies, which face challenges and certain risks in wafer manufacturing and capacity assurance.

In core computing scenarios such as autonomous driving, traditional general-purpose CPUs are difficult to adapt to AI computing requirements due to their low computing efficiency. AI chips such as GPUs, FPGAs, and ASICs have excellent performance on the edge and cloud due to their own characteristics and are more widely used. From the perspective of technology trends, GPUs will continue to dominate AI chips in the short term, and ASICs are the ultimate direction in the long term. From the perspective of market trends, global demand for AI chips will maintain a rapid growth momentum. Both cloud and edge chips have great growth potential. It is expected that the market growth rate will be close to 50% in the next five years. Although the foundation of domestic chip technology is relatively weak, with the rapid implementation of AI applications, the rapid increase in demand for AI chips has created opportunities for the growth of technology and capabilities of local chip companies. Autonomous driving has strict requirements on computing power, latency, and reliability. Currently, GPU+FPGA solutions are mostly used. In the future, as algorithms become more stable and data-driven, ASICs are expected to gain market space.

A lot of space is needed on the CPU chip for branch prediction and optimization, and to save various states to reduce the delay when switching tasks. This also makes it more suitable for logic control, serial operations, and general-type data operations. Taking the comparison between GPU and CPU as an example, compared with CPU, GPU uses a large number of computing units and a very long pipeline, with only very simple control logic and no cache. The CPU not only has a lot of space occupied by cache, but also has complex control logic and many optimization circuits. In comparison, computing power is only a small part.

Power domain control chip

The power domain controller is an intelligent powertrain management unit. It uses CAN/FLEXRAY to achieve transmission management, battery management, and monitor alternator regulation. It is mainly used for powertrain optimization and control, and also has functions such as electrical intelligent fault diagnosis, intelligent power saving, and bus communication.

(1) Work requirements

The power domain control MCU can support major power applications such as BMS, and its requirements are as follows:

High main frequency, main frequency 600MHz~800MHz

RAM 4MB

High functional safety level requirements, can reach ASIL-D level;

Support multi-channel CAN-FD;

Support 2G Ethernet;

Reliability no less than AEC-Q100 Grade1;

Support firmware verification function (national secret algorithm) ;

(2) Performance requirements

High performance: The product integrates the ARM Cortex R5 dual-core lock-step CPU and 4MB on-chip SRAM to support the growing demand for computing power and memory in automotive applications. The ARM Cortex-R5F CPU has a main frequency of up to 800MHz. High security: The automotive reliability standard AEC-Q100 reaches Grade 1 level, and the ISO26262 functional safety level reaches ASIL D. The dual-core lock-step CPU used can achieve up to 99% diagnostic coverage. The built-in information security module integrates a true random number generator, AES, RSA, ECC, SHA, and hardware accelerators that comply with national and commercial encryption standards. The integration of these information security functions can meet the needs of applications such as secure boot, secure communication, and secure firmware updates and upgrades.

Body domain control chip

The body domain is mainly responsible for controlling various functions of the body. With the development of the whole vehicle, there are more and more body domain controllers. In order to reduce the cost of the controller and the weight of the whole vehicle, integration requires all functional devices from the front part, the middle part and the rear part of the vehicle, such as the rear brake light, rear position light, tailgate lock, and even the double support rod to be integrated into a general controller.

The body domain controller generally integrates BCM, PEPS, TPMS, Gateway and other functions, and can also be expanded to add seat adjustment, rearview mirror control, air conditioning control and other functions, comprehensively and uniformly manage various actuators, and reasonably and effectively allocate system resources. The body domain controller has many functions, as shown in the figure below, but is not limited to the functions listed here.

Body domain controller function table

※Source: Public information, provided by the compilation unit

(1) Work requirements

The main demands of automotive electronics for MCU control chips are better stability, reliability, security, real-time and other technical characteristics, as well as higher computing performance and storage capacity, and lower power consumption index requirements. The body domain controller has gradually transitioned from decentralized functional deployment to a large controller that integrates all basic drives, key functions, lights, doors, windows, etc. of body electronics. The body domain control system design integrates the control of lights, wipers, central door locks, windows, etc., PEPS smart keys, power management, etc., as well as gateway CAN, scalable CANFD and FLEXRAY, LIN network, Ethernet and other interfaces and modules and other development and design technologies.

Generally speaking, the working requirements of the MCU main control chip for the above-mentioned control functions in the body domain are mainly reflected in the aspects of computing processing performance, functional integration, communication interface, and reliability. In terms of specific requirements, due to the large functional differences in different functional application scenarios in the body domain, for example, body applications such as electric windows, automatic seats, and electric tailgates also have the need for efficient motor control. Such body applications require the MCU to integrate functions such as FOC electronic control algorithms. In addition, different application scenarios in the body domain have different requirements for chip interface configuration. Therefore, it is usually necessary to select the body domain MCU based on the functional and performance requirements of the specific application scenario, and on this basis, comprehensively weigh factors such as product cost performance, supply capacity, and technical services.

(2) Performance requirements

The main reference indicators of body domain control MCU chips are as follows:

Performance : ARM Cortex-M4F @144MHz, 180DMIPS, built-in 8KB instruction cache, support Flash acceleration unit to execute program with 0 wait time.

Large - capacity encrypted memory: up to 512K Bytes eFlash, supporting encrypted storage, partition management and data protection, supporting ECC verification, 100,000 erase and write times, 10-year data retention; 144K Bytes SRAM, supporting hardware parity verification.

· Integrated rich communication interfaces: support multiple GPIO, USART, UART, SPI, QSPI, I2C, SDIO, USB2.0, CAN 2.0B, EMAC, DVP and other interfaces.

Integrated high-performance analog devices: support 12-bit 5Msps high-speed ADC, rail-to-rail independent operational amplifier, high-speed analog comparator, 12-bit 1Msps DAC; support external input independent reference voltage source, multi-channel capacitive touch button; high-speed DMA controller.

Support internal RC or external crystal clock input, high reliability reset.

Built - in calibrable RTC real-time clock, supporting leap year calendar, alarm events, and periodic wake-up.

Support high-precision timing counter.

Hardware - level security features: cryptographic algorithm hardware acceleration engine, support for AES, DES, TDES, SHA1/224/256, SM1, SM3, SM4, SM7, MD5 algorithms; Flash storage encryption, multi-user partition management (MMU) , TRNG true random number generator, CRC16/32 operation; support for write protection (WRP) , multiple read protection (RDP) levels (L0/L1/L2) ; support for secure boot, encrypted program download, and secure update.

Support clock failure monitoring and anti-tampering monitoring.

· With 96-bit UID and 128-bit UCID.

High reliability working environment: 1.8V～3.6V/-40℃～105℃.

(3) Industrial structure

The body domain electronic system is in the early stages of growth for both foreign and domestic companies. Foreign companies have deep technical accumulation in single-function products such as BCM, PEPS, doors and windows, and seat controllers. At the same time, the product lines of major foreign companies cover a wide range, laying the foundation for them to make system integration products. Domestic companies have certain advantages in the application of new energy vehicle bodies. Take BYD as an example. In BYD's new energy vehicles, the body domain is divided into three domains: left, right, and rear, and the system integration products are re-arranged and defined. However, in terms of body domain control chips, the main suppliers of MCUs are still international chip manufacturers such as Infineon, NXP, Renesas, Microchip, and ST, and domestic chip manufacturers currently have a low market share.

(4) Industry barriers

From a communication perspective, there is an evolution process from traditional architecture to hybrid architecture and finally to Vehicle Computer Platform. The changes in communication speed and the price reduction of basic computing power with high functional safety are the key. In the future, it is possible to gradually achieve compatibility of different functions at the electronic level of the basic controller. For example, the body domain controller can integrate traditional BCM, PEPS, ripple anti-pinch and other functions. Relatively speaking, the technical barriers of body domain control chips are lower than those of power domain, cockpit domain, etc. Domestic chips are expected to take the lead in making major breakthroughs in the body domain and gradually achieve domestic substitution. In recent years, domestic MCUs have had a very good development momentum in the front and rear end markets of the body domain.

Cockpit domain control chip

Electrification, intelligence, and networking have accelerated the development of automotive electronic and electrical architecture towards domain control, and the cockpit domain is also developing rapidly from in-vehicle audio and video entertainment systems to smart cockpits. The cockpit is presented as a human-computer interaction interface, but whether it is the previous infotainment system or the current smart cockpit, in addition to a SOC with powerful computing speed, a high-real-time MCU is also required to process data interaction with the entire vehicle. The gradual popularization of software-defined cars, OTA, and Autosar in the smart cockpit domain has made the requirements for cockpit domain MCU resources higher and higher. Specifically, the demand for FLASH and RAM capacity is increasing, and the demand for PIN Count is also increasing. More complex functions require stronger program execution capabilities, and at the same time, there must be more abundant bus interfaces.

(1) Work requirements

In the cockpit domain, the MCU mainly implements functions such as system power management, power-on timing management, network management, diagnosis, vehicle data interaction, buttons, backlight management, audio DSP/FM module management, and system time management.

MCU resource requirements:

There are certain requirements for the main frequency and computing power. The main frequency should not be less than 100MHz and the computing power should not be less than 200DMIPS;

The Flash storage space is not less than 1MB, with physical partitions for code Flash and data Flash;

· RAM no less than 128KB;

High functional safety level requirements, can reach ASIL-B level;

Support multi-channel ADC;

Support multi-channel CAN-FD;

Automotive grade AEC-Q100 Grade1;

Support online upgrade (OTA) , Flash supports dual banks;

· It needs to have an information encryption engine of SHE/HSM-light level or above and support secure boot;

· Pin Count is not less than 100 pins;

(2) Performance requirements

IO supports wide voltage power supply (5.5v~2.7v) , and IO port supports overvoltage use;

Many signal inputs fluctuate according to the voltage of the power supply battery, and there is an overvoltage input situation. The IO port supports overvoltage use to improve system stability and reliability.

Memory life:

The life cycle of a car is more than 10 years, so the program storage and data storage of the car MCU need to have a longer life. Program storage and data storage need to have separate physical partitions. The program storage has a small number of erase and write times, so Endurance>10K is sufficient. Data storage needs to be erased and written frequently, so a larger number of erase and write times is required. Refer to the data flash indicator Endurance>100K, 15 years (<1K) , 10 years (<100K) .

Communication bus interface;

The bus communication load in automobiles is getting higher and higher, so traditional CAN can no longer meet the communication needs. The demand for high-speed CAN-FD bus is getting higher and higher, and support for CAN-FD is gradually becoming a standard feature of MCUs.

(3) Industrial structure

At present, the proportion of domestically produced smart cockpit MCUs is still very low, and the main suppliers are still international MCU manufacturers such as NXP, Renesas, Infineon, ST, Microchip, etc. There are many domestic MCU manufacturers who have already made plans, and their market performance remains to be seen.

(4) Industry barriers

The automotive grade and functional safety grade of smart cockpits are relatively low, mainly due to the accumulation of know-how, which requires continuous product iteration and improvement. At the same time, since there are not many domestic wafer factories with automotive MCU production lines and the process is relatively backward, it will take some time to run-in if a national supply chain is to be realized. At the same time, there may be higher costs, and the competition pressure with international manufacturers is greater.

Application of domestic control chips

Automotive control chips are mainly automotive MCUs. Leading domestic companies such as Unigroup Guoxin, Huada Semiconductor, Shanghai Xinti, GigaDevice, Jiefa Technology, Xinchi Technology, Beijing Junzheng, Shenzhen Xihua, Shanghai Qipuwei, and National Technology all have automotive-grade MCU product series, which are benchmarked against the products of overseas giants. They are currently mainly based on ARM architecture, and some companies have also carried out research and development of RISC-V architecture.

At present, domestically produced vehicle control domain chips are mainly used in the automotive pre-installation market, and have been applied in the body and infotainment domains. In the fields of chassis and power, they are still dominated by overseas chip giants such as STMicroelectronics, NXP, Texas Instruments, and Microchip Semiconductor. Only a few domestic companies have achieved mass production applications. At present, the domestic chip manufacturer Xinchi released the high-performance control chip E3 series in April 2022. The product is based on ARM Cortex-R5F, with a functional safety level of ASIL D, a temperature level that supports AEC-Q100 Grade 1, a CPU main frequency of up to 800MHz, and up to 6 CPU cores. It is the highest-performance product among the existing mass-produced automotive MCUs, filling the gap in the domestic high-end and high-safety level automotive MCU market. With high performance and high reliability, it can be used in core vehicle control fields such as BMS, ADAS, VCU, wire-controlled chassis, instruments, HUD, and smart rearview mirrors. There are more than 100 customers who use E3 for product design, including GAC, Geely, etc.

Application of domestic controller chip products