Anti-Lock Braking System (ABS) Block Diagram

 Design Considerations

An anti-lock braking system (ABS) is a safety system that allows the wheels on a motor vehicle to continue interacting with the road surface as directed by driver inputs while braking, thus preventing the wheels from locking up and avoid skidding. An ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces for many drivers.

The primary input of the ABS system is the wheel speed sensor interface. Comparison of wheel speed sensor inputs can determine if individual wheels are slipping. Wheel speed sensors are typically Hall Effect, with preconditioning required to generate a readable digital PWM input to the MCU.

Microcontroller – An automotive-grade ARM based microcontroller is used to compare speed sensor data, control brake cylinder pressure and control the return pump for each wheel brake cylinder. The MCU is also responsible for diagnostics, warning notification and communication with other on board control units. Newer automotive MCUs from TI can provide evidence of their suitability for use in systems where IEC61508 and ISO26262 safety standards compliance may be required.

Anti-Lock Braking IC – The TPIC7218 is an antilock brake controller designed for use in harsh automotive environments, requiring few external components. It has eight high current low-side drivers for use with solenoid valves, four configurable wheel speed sense inputs capable of handling both Intelligent and Active sensors, and high-side gate drivers for controlling two external N-channel MOSFETs for use with a pump motor and master relay.

Power Management – The TPS65381-Q1 is a multi-rail power supply designed to supply microcontrollers in safety-critical applications, such as those found in automotive. The devices supports Texas Instruments' TMS570LS series 16/32-bit RISC flash MCU and other microcontrollers with dual-core lockstep (LS) or loosely coupled architectures (LC).

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