Test Equipment Development and Failure Diagnosis Using Sensor Emulators Built with CMOS Analog Multiplexers

Testing is a key phase during development of an automotive electronic product. By testing, the hardware design and the system integration are validated, and the reliability of the electronic devices and systems is proven. The development of the test equipment is part of this process, and it is intended to provide the appropriate test environment for the target ECU (Electronic Control Unit) under test. This article describes a hardware implementation of a sensor emulator with CMOS analog multiplexers. Many types of automotive sensors generate rectangular output signal(s), following different protocols and standards. There are sensors with pure digital output level (TTL or CMOS standard levels), PWM (Pulse Width Modulation) or various communication protocols (SENT, PSI5 etc). During verification and validation testing of electronic circuit interfaces where these sensors are connected, no real sensor is used, but an emulator equipment which is capable to generate signals with the same parameters as original sensor. Beside generation of identical signals, the emulator must be capable to adjust various parameters (like voltage or current levels, slew rates, pulse widths, etc) in order to test the behavior of the DUT (Device Under Test) in case of deviations of these parameters beyond the nominal ranges. The CMOS analog multiplexers offers some advantages in sensors emulation implementation, like simplified schematic and easy parameter adjustment of the output signal. Overall, the test equipment size and cost is reduced.