The next generation of door area system IC will greatly improve energy efficiency and promote vehicle electrification

In recent years, the electrification of automobiles is the general trend. The electrification of automobiles is not only the introduction of pure electric vehicles, but also the continuous replacement of traditional mechanical components and mechanical relays with Electronic control technology, or the introduction of new functions in some cases.

The large-scale electrification of automobiles is driving the development of autonomous driving to a higher level. In the medium and long term, many vehicles may be regarded as “unmanned taxis.” According to this new car driving concept, all functions in the door will be automated, for example, intelligent automatic door opening and anti-collision detection. These automated systems will be able to detect that pedestrians or cyclists are approaching the car and automatically control the door opening operation to avoid collision hazards. In the future, advanced sensors will be installed in the door to detect obstacles outside the door to prevent the door from being damaged.

The emergence of the megatrend is inseparable from the paving of dedicated semiconductor chips. These chips need to follow advanced power management concepts to drive milliwatt-level loads from LEDs to high-power DC motors whose instantaneous dissipation power can easily reach 200W. In addition, automotive electronic modules also need to be equipped with highly standardized communication interfaces, such as CAN and LIN physical layers.

How to determine a correct system architecture to implement new functions at a reasonable cost without affecting quality and performance is a major challenge faced by automakers. As the cost and complexity of software and hardware development continue to increase, it becomes more and more difficult to keep up with the performance and functional requirements of OEMs. In addition, OEM manufacturers also require the deployment of cost-effective and scalable solutions to expand from low-end models to high-end vehicles, sharing development costs on different platforms and models.

The door area electronic control module (Figure 1) is a familiar automotive system that benefits from a scalable driving method. The application concept is to use an IC to drive multiple loads in the door area (door lock motor, adjustable foldable rear view) Mirror, defroster, window lift motor and LED, incandescent lamp and other lighting functions). The expandable driver, the package and the software are compatible with the entire system, and adapt to the diversified requirements of the door electronic control module, which is a typical feature of the door area actuator.

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In the past 10 years, automotive semiconductor manufacturers have developed a number of door actuator driver chips. As the number of automotive electrical loads continues to increase, new functions have been added to these products, and packaging and chip manufacturing technologies and IP cores have been developed. optimization. Among the electronic components in the door area, in addition to the driver chip (Figure 2), there is also a power management IC, which provides a stronger system power supply for the electronic control unit, including various standby modes and communication layers (mainly LIN and/or HS CAN). The power management chip usually integrates two low-dropout voltage regulators to supply power to the system microcontroller and peripheral loads (peripherals such as sensors). It also includes an enhanced system standby function and configurable local and remote wake-up functions.

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Both the door actuator driver and the power management chip use STMicroelectronics’ BCD (Bipolar, CMOS and DMOS) semiconductor manufacturing technology optimized for this application. The driver chip of the door actuator adopts 0.7μm BCD technology, and the power management chip adopts 0.57μm BCD technology.

In order to comply with the new development trend of automotive technology, automotive semiconductor devices must efficiently and safely control more electrical loads, minimize quiescent current, and at the same time adopt highly integrated solutions to reduce the number of components, reduce circuit board space, and reduce The weight of the product greatly simplifies the design.

ST’s proprietary advanced 0.16μm BCD8S is the key technology to realize the unique highly integrated monolithic solution on the market (Figure 3), which can meet the technical requirements of power management, fault protection and door load drive applications. This technology can also improve energy efficiency and computing power, increase the junction temperature of the chip to 175°C, and reach the standard junction temperature strictly specified by automotive OEM manufacturers, and it is extremely challenging to crack the monolithic integrated power management and actuator drivers. Thermal management problems.

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ST’s innovative L99DZ100G/GP front door controller chip and L99DZ120 rear door controller chip help designers save space while improving the reliability and energy efficiency of the door control module.

The previous ASSP (Special Standard Product) solution for the door area required 2 chips: a 12mm×12mm (TQFP64) door actuator driver and a 10mm x 10mm (PowerSSO-36) power management chip, while the STMicroelectronics door The area control monolithic solution only needs a LQFP64 with the same package area as TQFP64 (Figure 4), which is very important for the miniaturization of PCB circuit boards and can meet more stringent space requirements. In addition to using the new BCD technology to reduce the die size, a new innovative packaging structure is also used to reduce the packaging area. While shrinking the door system IC, it also improves the peak output current and power density.

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The software of all products is compatible with each other, which also helps simplify development and shorten product market time.

ST’s proprietary BCD8S advanced automotive technology plays a key role in realizing this monolithic solution. The solution has multiple functions, including a built-in half bridge and a high-side driver up to 7.5A, which can meet the new requirements of door area applications. The solution also integrates high-speed CAN (HS-CAN) and LIN 2.2a interfaces (SAE J 2602), control modules and protection circuits. In addition to the standard features, L99DZ100GP also supports selective wake-up of the ISO 11898-6 HS-CAN standard, allowing ECUs that are not frequently used to enter sleep mode, while maintaining the connection with the CAN bus, maximizing energy-saving effects.

Both front door controllers integrate MOSFET half-bridges, which can drive up to five DC motors and an external H-bridge. In addition, the two chips have eight LED drivers and two incandescent lamp drivers, a rear-view mirror heater gate driver, and a window electrochromic glass control module. Other features include voltage regulators for external circuits (microcontrollers, sensors, etc.), as well as related timers, watchdogs, reset generators and protection functions. The rear door controller L99DZ120 also has similar functions, for example, a power window lifter motor driver.

Equipping vehicles with more electronic systems and functions helps increase the car’s selling point, but more electronic configurations also increase power requirements. Therefore, it is necessary to accurately analyze the power consumption of each system under various working conditions, especially for pure electric vehicles. The waste of electricity is equivalent to shortening the cruising range; the more electrical components, the greater the leakage current, which is inevitable. Therefore, all car manufacturers value products and/or technologies with low quiescent current and standby current. Most ECUs have a maximum standby current budget of 100μA, so customers often say: “Each microamp is important.”

Therefore, STMicroelectronics has integrated an advanced power management module with multiple low quiescent current modes on the new door area controller chip (standby/sleep, periodic monitoring, dedicated low current mode LDO regulator, timer, contact device power supply) ). In the VBAT standby mode, the quiescent current drops below 10μA, which is within the range of 7μA-8μA, which is one-half of the topological structure of the dual-chip IC (door area driver IC + power management IC). For door applications, the controller does not supply power to the microcontroller (MCU) until the voltage regulator is awakened through the physical layer of the external contact device monitoring or communication interface (LIN, HS-CAN, or HS-CAN that supports selective wake-up).

ST’s new door area controller not only integrates the previous door area actuator driver chip and power management chip in one package, but also adds some new functions to better serve the new automotive development trends.

In order to support the automatic LED duty cycle compensation function, STMicroelectronics’ new door zone controller implements a new IP module. The internal compensation algorithm uses the measured value of the power supply voltage to correct the duty cycle of the LED driver power stage to ensure that the LED is in the ECU power supply. It can maintain uniform brightness even when the voltage fluctuates. Developers can flexibly set the duty cycle compensation function according to different loads, use different LEDs and series LEDs, thereby saving the load of the external microprocessor and minimizing the data flow of SPI.

The thermal cluster concept is another new feature of the new controller. When short-circuit events occur, this feature can individually disable the short-circuited output channels, and other output channels will keep working normally.

In order to meet the requirements for safe operation of power windows, the new controller also implements a dedicated IP core, which can make the windows enter a safe state in the event of a system error, avoiding the out-of-control movement of the windows. According to safety requirements, there is a deep trench isolation layer between the IP core and the rest of the chip, which is another valuable feature of BCD8s technology. The self-biasing method enables the IP module to work normally when the battery is dead.

The L99DZ100 series products support the most advanced automotive door electronic applications. However, with the development of automotive technology, there will be new demands in the future, for example, to drive more DC high-power motors. To this end, STMicroelectronics adopts a modular approach to develop these chips, which can integrate more IP cores in the new configuration and upgrade and expand the door area control system. In addition to door applications, the new series of products will also be used in other automotive systems to drive loads in an optimal way. For example, electric trunk lid modules or sunroofs have similar system requirements. In the future, dedicated ASSPs will also enter this market segment.