Semiconductor solutions for braking systems: New partitioning and new safety concepts increase safety and reduce system cost

摘要

Braking systems require a high system safety level: New safety concepts need to be implemented by reducing the system complexity. Microcontrollers with special safety functions are available with implemented features, self-detecting and compensating different types of faults. Today usually two microcontrollers are used to check each other. Power devices provide microcontroller supplies and drive motors and valves; internally the functions are supervised to avoid incorrect system behavior due to wrong voltages, currents, missing loads or other malfunctions. Bus interfaces, signal conditioning and interfaces for high voltage signals are integrated into the power system ICs. Latest BIPOLAR-CMOS-DMOS power technologies enable the power semiconductors to integrate logic functions. This capability drives new partitioning of power ICs and microcontroller in ABS and ESP systems: Calculation tasks and microcontroller supervision functions migrate from the microcontroller into the power devices Power devices get intelligence. Today, the microcontroller is loaded with current measurement and the generation of duty cycles to control the target pressure for each wheel. Intelligent power devices take over the current regulation control loop. The increasing data transfer between components and modules requires advanced interfaces as well as enhanced data coding and supervision. New balancing between the pure CMOS microcontroller and BCD mixed-signal power ICs is established. Individual component cost may increase, but the overall system cost is reduced with a higher safety level.