An automotive multi-chip module for rotational speed and direction measurement

This paper focuses on the issues concerning the system design of an IC implementation of a new integrated sensor and signal conditioning module for automotive anti-locking brake systems (ABS). It describes a concise solution for the detection of the speed and direction of rotation of a car-wheel. The signal conditioning is realised by digital control of analog elements and a new signalling protocol is detailed which transmits information via modulation of the supply current. The system functions in a harsh operating environment to above 150°C, with the external supply voltage varying from 40 V to 4.5 V, and features robust EMC performance. It is realised as a Multi Chip Module (MCM) in BiCMOS/DMOS (BCD) and CMOS processes, and is completely contained in a two pin package with no external components. (6 pages)