Ultrasonic parking distance measurement with automotive ToF sensor
To measure the distance to an obstacle, the NCV75215D time-of-flight (ToF) sensor from onsemi features high-sensitivity, low-noise operation and enables detection from 0.25m up to 4.5m for a pole measuring a standard 75mm.
Operating with a piezoelectric ultrasonic transducer, the NCV75215D determines minimum distance by the length of reverberations. When the external analog circuit is perfectly tuned and matched, the ToF sensor can reduce the minimum distance to 0.2m.
The ultrasonic transducer is driven with a programmable frequency via a transformer. The echo which is received is amplified and converted to a digital signal. The digital signal is filtered and detected, so the magnitude can be compared to a time-dependent threshold which is stored in an internal RAM.
The time measured from a transmission burst to echo recognition determines the distance to the obstacle. Communication with a master (ECU) is over a bidirectional I/O line for commands to the NCV75215 and the return of the reported data.
For applications from static to high speed, there is also the NCS32100 inductive position sensor which features battery backup to provide high-accuracy angular sensing when paired with a contactless PCB sensor.