Preface
In the last issue of the "Difficult Substitution" series, we introduced an important classification of BMS chips - AFE chips, and in this issue we introduce another important class of BMS chips - digital isolation chips: Review of the last issue of "Difficult Substitution - Automotive-grade AFE Chips"
The importance of digital isolation chips
The application of isolation technology is becoming increasingly important in modern electronic systems, especially in scenarios that ensure safe and reliable communication between high and low voltage modules. The isolation device achieves galvanic isolation by converting and passing the input signal to the output, thus ensuring safe signal transmission between high voltage (strong current) and low voltage (weak current). This technology not only helps to prevent damage caused by the direct flow of strong currents due to faults to weak circuits, but also eliminates the ground loop between the two circuits, effectively blocking interfering signals such as common mode and surges, and improving the safety and reliability of the entire electronic system. As an important branch of isolation technology, digital isolation chips have a wide range of product definitions and application scenarios, especially in the automotive field. The digital isolation chip achieves a high degree of integration by integrating power isolation and signal isolation on a single chip, while reducing the cost and size, and providing a better technical solution. These chips are primarily used for digital communication between high and low voltages, such as serial peripheral interface (SPI) communication between high-voltage sampling and microcontrol units (MCUs) on the main control board of the battery management system (BMS), and SPI communication between the analog front-end (AFE) of the sampling board and the MCU. In automotive applications, the importance of digital isolation chips cannot be underestimated. As electric and hybrid vehicles evolve, high-wattage power electronics in these vehicles, such as on-board chargers (OBCs), DC/DC converters, and motor-controlled drive inverters, require highly reliable galvanic isolation to ensure safety and performance. Digital isolation chips play a key role in these applications, not only for the isolation of control communications such as CAN and LIN buses, but also for isolated driver ICs that drive MOSFETs or IGBTs, and isolated ADCs/isolated op amps for current and voltage sampling. The isolation chip not only improves the safety of the system, but also effectively isolates high voltage and signal interference, especially in the battery management system (BMS) of the energy storage power station, which ensures the stable and safe operation of the system through inter-board communication.
Schematic diagram of NOVOSENSE high-voltage energy storage BMS isolation product, source: NOVOSENSE official website
Digital isolation chip market size forecast
Digital isolation chips play an increasingly important role in modern electronic systems, especially in the fields of new energy power generation, energy storage systems and electric vehicles. These chips are mainly used in inverters, converters, PCS and other equipment in new energy power generation and energy storage systems, and are responsible for achieving key functions such as electrical isolation, signal sampling, and communication.
The application of digital isolation chips in new energy vehicles, source: Essence Securities Research Center
In electric vehicles, isolation chips are used in several critical systems, including on-board chargers, battery management systems (BMS), DC/DC converters, motor control drive inverters, and CAN/LIN bus communications. As electric vehicles migrate to 400V to 800V high-voltage systems, these applications require higher performance requirements for isolation chips, including stronger isolation withstand voltage and faster fault detection capabilities to ensure the stability and safety of high-voltage systems.
全球数字隔离芯片下游引用占比（2020年），来源：Markets and Markets
According to Markets and Markets, the global digital isolation chip market is expected to be worth USD 1.8 billion in 2022 and is expected to grow to USD 2.7 billion by 2027, with a CAGR of 8.45%. This growth is mainly driven by two major application segments, industrial and automotive, which accounted for 28.58% and 16.84% of the market in 2020 and are expected to reach 28.80% and 16.79%, respectively, by 2026.
全球数字隔离芯片市场规模预测，来源： Markets and Markets
European and American semiconductor companies such as TI, Silicon Labs, and Analog Devices dominate the digital isolation chip market, and their technological advancement and broad product lines enable them to meet the growing market demand. At the same time, some Chinese companies such as NOVOSENSE and Rongpai Semiconductor are also actively deploying in this field and gradually increasing their market share. These companies are gradually changing the competitive landscape of the market by providing products with performance that can compete with international manufacturers.
Digital Isolation Chip Technology Trends
The technical route of the isolation chip mainly includes opto-decoupling isolation, capacitive coupling isolation and magnetic decoupling isolation. Although optocouplers were the first isolation technology used, their low dielectric strength made it difficult to achieve a high level of isolation. The capacitive coupling technology realizes the isolated transmission of signals through the principle of capacitance, which has the characteristics of long life, low power consumption and high transmission rate, but its surge protection ability is limited. In contrast, magnetic isolation technology performs better in high-frequency DCDC power conversion, can transmit higher power signals, improves transmission delay and delay skew, and is suitable for applications that require high-frequency signal transmission. The types of isolation technologies mainly include magnetic inductive isolation (magnetic coupling), capacitive coupling isolation (capacitive coupling), and giant magnetoresistive isolation. Among them, capacitive couplers and magnetic couplers are widely favored by the market because of their excellent performance. Capacitive coupling technology typically uses silica (SiO2) or polyimide (Polyimide) as an insulating medium, which has high withstand voltage characteristics and excellent isolation strength. For example, capacitive silica can withstand pressures of 500 volts per micron, while polyimide is about 300 volts per micron.
Mainstream architecture and its progress
In the development of technology, Pulse modulation and OOK modulation architecture are more common transmission modes, characterized by low power consumption and high transmission rate, but are prone to data errors in strong interference environments. In order to improve the reliability and anti-interference ability of the system, a new generation of modulation technology Pulse-Coding came into being. This technology uses edge coding technology to enter a sleep state after data transmission is completed, which significantly reduces power consumption and improves anti-interference ability. In addition, Pulse-Coding technology can achieve common-mode transient immunity (CMTI) of up to 200Kv/uS.
The importance and development of CMTI technology
In terms of CMTI technology, isolators need to handle rapidly changing perturbation signals without affecting the output. The use of high CMTI technology, such as fully differential transmitter and receiver architecture, equivalent common-mode input impedance control and digital filtering technology, can effectively improve the stability and accuracy of the signal. The fully differential architecture provides higher signal integrity, the equivalent common-mode input impedance control technique ensures that the signal remains stable in high-disturbance environments, and the digital filtering technique sacrifices part of the transmission rate in exchange for better interference immunity.
Implementation of high CMTI technology
For example, the high-CMTI technology developed by Chuantu Microelectronics effectively controls the common-mode level through an innovative receiver circuit design, and maintains a stable signal output even under extreme disturbance conditions. In addition, the use of digital filtering technology can effectively reduce the bit error rate and improve the reliability of the overall system.
Challenges and countermeasures of electromagnetic interference (EMI).
On the other hand, isolated devices are also challenged by electromagnetic interference (EMI). To this end, various techniques such as frequency jitter technology, the use of metal shields, and high-gain receiver circuit design are used to reduce the effects of EMI. In particular, the capacitive-coupled architecture transmits signals through an electric field, which has less natural radiation than the magnetic field transmission of the magnetic coupling. This strategy not only improves the device's immunity to interference, but also helps to reduce the overall power consumption of the device.
The benefits of highly integrated technology
In terms of the high integration of isolation technology, the fully integrated isolated DC-DC technology shows extremely high integration and conversion efficiency. This technology integrates an isolated power module, a digital isolator, and a digital isolated interface into a single device, significantly reducing package size and improving efficiency. For example, integrated chips can achieve higher performance in smaller packages, which is a huge advantage for device manufacturers as it reduces the footprint of the circuit board and lowers the overall system cost. Therefore, the development of digital isolation technology not only focuses on a single transmission efficiency or isolation capability, but also pays more attention to the reliability, integration and resistance to environmental interference of the overall solution. With the application of the third generation of semiconductor technology and the changes in market demand, the technical route and trend of digital isolation devices will continue to develop in the direction of high performance, low power consumption and high integration.
Introduction to mainstream automotive-gauge digital isolator players
According to the collation with the non-research institute, the mainstream automotive digital isolator manufacturers in the market include Analog Devices, Texas Instruments, Silicon Labs, Infineon, STMicroelectronics, Sijiaxun, Egoro, onsemi, NVE, Vicor, Toshiba, NOVOSENSE, Zhixin, Shuming, Gree Micro Technology, Rongpai, Chuantu Micro, Siruipu, Huada Semiconductor, Jingkong, Sipeng, Zhanxin, etc. The following are some of the players who have been sorted out with non-research institutes:
Some mainstream automotive isolators are the original manufacturers, source: and non-research institutes
TI offers a range of silica gate-based digital isolation products that offer low power consumption and high efficiency, making them ideal for applications that require high isolation performance and high data rates. ADI is known for its magnetically coupled isolation technology, which offers data rates up to 200Mbps, and is designed with multi-channel flexibility and robustness for a wide range of complex electronic control systems. Infineon's ISOFACE family offers high-performance isolation solutions with a particular focus on miniaturization and low power consumption with a focus on coreless transformer technology, suitable for modern and demanding electronic devices. NOVOSENSE is a leading manufacturer of digital isolation chips in China, using Adaptive OOK technology and high-voltage isolation process to provide high-performance and low-cost isolation solutions, which have been widely used in automotive and industrial control systems. Zhongke Geli Micro and Rongpai Semiconductor are unique in the market with their unique magnetic coupling and capacitive isolation technologies, respectively, providing high-speed and low-power products, suitable for new energy vehicles and smart meters and other fields. As an emerging start-up, Rayabor focuses on reducing costs by optimizing architectures and focusing on meeting specific industry needs, such as power and energy storage. BGI's HSA6880-Q products use magnetic isolation technology, which has reached the automotive-grade standard and is widely used in the electronic control system of new energy vehicles. Zhixinwei's SCCK11410/1/2 series achieves an isolation voltage of up to 5000Vrms through an advanced silicon oxide double-layer capacitor isolation structure, with excellent data transmission stability and anti-electromagnetic interference capabilities. Shuming Semiconductor's SiLM572x and SiLM574x series support data rates up to 100Mbps with low propagation delay and high common-mode transient immunity, making them ideal for automotive and industrial applications. The company has developed small-volume and high-efficiency isolated DC-DC conversion chips, such as the Gip50XX series, which are suitable for low-power signal isolation applications. SRP's TPT772x and TPT774x series offer high-speed data transmission and excellent electromagnetic compatibility, as well as low-power operation for use in noisy industrial environments. Chuantu's CA-IS303xT product is a high-performance isolated LVDS buffer that provides up to 3750VRMS isolation withstand voltage and 1.1Gbps data transmission capability, making it ideal for high-end analog signal and data transmission applications. Known for its expertise in energy efficiency and IoT chips, Silicon Friends has developed a wide range of industrial-grade dedicated processors and power management solutions. Its flagship product SSP584X series of digital isolators, featuring high speed, low power consumption, high isolation voltage and excellent anti-interference performance, is suitable for new energy management systems and integrated circuit design. Junxin excels in the field of single-channel gate driver ICs, and its IVCO1A0x series products provide high insulation withstand voltage and high transmission efficiency through capacitive isolation technology. These chips not only support automotive-grade applications, but are also widely used in industrial power supplies, motor control, and power conversion systems. The high current drive capability and compact package design of the IVCO1A0x series give it significant advantages in high-frequency switching applications, while also ensuring system reliability and safety in harsh environments.
summary
With the development of these trends, it is expected that the demand for isolation chips will maintain a rapid growth trend in the future, especially in the field of new energy vehicles with high voltage and high safety requirements. It is expected that with the further popularization of new energy vehicles, the demand for isolation chips in key areas such as battery management systems and power systems will maintain a growth momentum. Despite the late start, the strong demand for domestic substitution and the active promotion of the market have given birth to a number of high-quality domestic digital isolation chip manufacturers. Through technological innovation, these manufacturers have been able to match or even surpass international brands in some key performance indicators. At present, domestic isolation chips are developing in the direction of high integration and vehicle-grade applications, showing the competitiveness of domestic manufacturers in the global market. In the face of competition from foreign companies, the rapid development of Chinese manufacturers in the field of isolation chips shows their competitive potential in the global market. With the continuous increase of Western countries' sanctions on China's semiconductors, independent innovation and technological independence in the domestic market have become particularly critical. It is believed that by increasing R&D investment and optimizing production processes, domestic enterprises can not only meet the domestic market demand, but also occupy a place in the international market.