he sensors to be tested are based on the Hall principle, offering a 360° measurement range. The output signal is PWM coded. The test program has been developed with LabView from National Instrument; the company however can also supply a home-grown test software which includes standard audio and video analysis facilities. The software can be adapted to a large number of different sensors. DUTs (Devices under Test) identified as faulty are destroyed automatically through an overvoltage.
Initially in the test course the signal waveform is programmed. The package features of the DUT are checked through light and colour sensors to ensure the test process suits the respective sensor type. Then the mechanical level of the sensor is operated through a precision drive while the sensor signal is recorded. "Since the sensors have a resolution of 12 bit the mechanical system must be absolutely clearance-free to get reproducible results", says system developer Julio Chamorro.