Principle Analysis of IC Driven Automotive Door Automation

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

The emergence of the general trend is inseparable from the paving of special semiconductor chips. These chips need to follow the advanced power management concept to drive high-power DC motors from milliwatt loads such as LEDs to instantaneous dissipated power that 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 realize new functions at a reasonable cost without affecting quality and performance is a major challenge for automobile manufacturers. With the increasing cost and complexity of software and hardware development, it becomes more and more difficult to keep up with the performance and functional requirements of OEM manufacturers. In addition, OEM manufacturers also require to deploy cost-effective and scalable solutions, expand from low-end models to high-end vehicles, and share development costs on different platforms and models.

The door area electronic control module (Figure 1) is a familiar automobile system benefiting from the scalable driving method. This application concept uses one IC to drive multiple loads in the door area (door lock motor, adjustable folding rearview mirror, defroster, window lifting motor, led, incandescent lamp and other lighting functions). The expandable driver, package and software are all compatible, and meet the diversified requirements of door electronic control module. It is a typical feature of door area actuator.

Figure 1:

In the past 10 years, automotive semiconductor manufacturers have developed several door actuator driver chips. With the increasing number of automotive electrical loads, new functions have been added to these products, and the packaging, chip manufacturing technology and IP core have been optimized. In the electronic components in the door area, in addition to the drive chip (Fig. 2), there is also a power management IC to provide stronger system power 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-voltage differential regulators to supply power to the system microcontroller and peripheral loads (peripherals such as sensors). It also includes enhanced system standby function and settable local and remote wake-up functions.

Figure 2:

The door actuator driver and power management chip adopt STMicroelectronics, for which BCD (bipolar, CMOS and DMOS) semiconductor manufacturing technology specially optimized is applied. The driver chip of door actuator adopts 0.7 μ M BCD technology, the power management chip adopts 0.57 μ M BCD technology.

In order to comply with the development trend of new automotive technology, automotive semiconductor devices must efficiently and safely control more electrical loads, minimize static current, and adopt high integration solutions to reduce the number of components, reduce the space of circuit board and reduce the weight of products, so as to greatly simplify the design.

STMicroelectronics proprietary advanced 0.16 μ M bcd8s is the key technology to realize the unique high integration monolithic solution in the market (Figure 3), which can meet the technical requirements of applications such as power management, fault protection and door load drive. This technology can also improve energy efficiency and computing power, increase the junction temperature of the chip to 175 ° C, meet the standard junction temperature strictly stipulated by automobile OEM manufacturers, and solve the challenging thermal management problems brought by monolithic integrated power management and actuator driver.

Figure 3:

Italy France semiconductor's innovative l99dz100g / GP front door controller chip and l99dz120 rear door controller chip help designers save space and improve the reliability and energy efficiency of door control module.

The previous door area ASSP (special standard product) solution required two chips: one 12mm × 12mm (tqfp64) door actuator driver and a 10mm x 10mm (powerso-36) power management chip, while the door area control monolithic solution of STMicroelectronics only needs an lqfp64 with the same packaging area as tqfp64 (Fig. 4), which is very important for the miniaturization of PCB circuit board and can meet more stringent space requirements. In addition to using the new BCD technology to reduce the bare chip size, it also reduces the packaging area through the new innovative packaging structure, which not only reduces the door system IC, but also improves the output current peak and power density.

Figure 4:

The whole product software is compatible with each other, which also helps to simplify development and shorten product market time.

Italy France semiconductor's proprietary bcd8s advanced automotive technology plays a key role in realizing this monolithic solution. The solution has a variety of functions, including built-in half bridge and 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 interface (SAE J 2602), control module and protection circuit. In addition to the standard features and functions, l99dz100gp also supports the selective wake-up of ISO 11898-6 hs-can standard, allowing the ECU with low frequency to enter the sleep mode, while maintaining the connection with the CAN bus to maximize the energy-saving effect.

Both front door controllers have integrated MOSFET half bridge, which can drive up to five DC motors and an external H-bridge. In addition, the two chips also have eight LED drivers and two incandescent lamp drivers, a rearview mirror heater grid driver and a window electrochromic glass control module. Other features include external circuits (microcontrollers, sensors, etc.) voltage regulators, as well as related timers, watchdog, reset generator and protection functions. The rear door controller l99dz120 also has similar functions, such as power window lifting motor driver.

Equipping the vehicle with more electronic systems and functions helps to increase the selling point of the vehicle, but more electronic configurations also improve the power requirements. Therefore, it is necessary to accurately analyze the power consumption of each system under various working conditions, especially for pure electric vehicles. Wasting power is equal to shortening the mileage; The more electrical components, the greater the leakage current, which is inevitable. Therefore, all automobile manufacturers attach great importance to products and / or technologies with low quiescent current and standby current. The maximum standby current budget of most ECUs is 100 μ A. Therefore, customers often say, "every micro safety is very important".

Therefore, STMicroelectronics integrates an advanced power management module with multiple low quiescent current modes (standby / sleep, regular monitoring, special low current mode LDO regulator, timer, contact equipment power supply) on the new door area controller chip. In Vbat standby mode, quiescent current drops to 10 μ Below a, at 7 μ A－8 μ Section a is half of the topology of dual IC (door area drive 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 external contact equipment monitoring or communication interface (Lin, hs-can or hs-can supporting selective wake-up).

The new door area controller of STMicroelectronics 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 automobile development trend.

In order to support the automatic led duty cycle compensation function, the new door area controller of STMicroelectronics implements a new IP module. The internal compensation algorithm uses the measured value of power supply voltage to correct the duty cycle of LED driver power level, so as to ensure that the LED can maintain uniform brightness when the ECU power supply voltage fluctuates. Developers can flexibly set the duty cycle compensation function according to different loads, and use different LEDs and series LEDs, so as to save the load of external microprocessors and minimize the data flow of SPI.

The concept of thermal clustering is another new feature of the new controller. In case of short circuit and other events, this feature can disable the short-circuit output channel separately, and other output channels remain normal.

In order to meet the requirements of safe operation of electric window, the new controller also implements a special IP core, which can make the window enter a safe state in case of system error and avoid out of control of window lifting action. According to the security 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 bias method enables the IP module to work normally when the battery is dead.

L99dz100 series products support the most advanced door electronic applications at present. However, with the development of automotive technology, new demands will emerge in the future, such as driving more DC high-power motors. To this end, STMicroelectronics adopts a modular method 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, the electric trunk lid module or sunroof has similar system requirements. In the future, dedicated ASSP will also enter this segment.