This solution is built around ON's NCV75215, an Application Specific Standard Part (ASSP) dedicated to ultrasonic parking distance measurement. The chip's main purpose is to drive a piezoelectric ultrasonic transducer and measure the Time Of Flight of echoes from obstacles while the vehicle is parking. The solution offers high sensitivity, low noise and excellent overall performance. The device is compliant with AEC-Q100 and PPAP.
Key Points
- TSSOP16 package with a high level of integration, compact footprint and easy soldering
- Integrated with the transducer element to form a fully digital sensor head, delivering stronger noise immunity
- As a dedicated ASSP, it provides better sensor-to-sensor consistency
- Key parameters such as transmit power, echo gain and receive sensitivity are software configurable
Solution Overview
The system is split into two modules: the ECU and the sensor head. The NCV75215 and the ECU communicate over a 3-wire interface to handle parameter configuration, status readback, distance measurement and other commands. The ECU issues a measurement command to tell the NCV75215 to start measuring. On receiving the command, the NCV75215 drives the transmit/receive ultrasonic sensor to send the ultrasonic burst and pick up the obstacle echo; the chip amplifies the received echo, performs analog-to-digital conversion and digital filtering, then returns the digitized waveform to the ECU over the communication interface. The ECU analyzes the received waveform for distance calculation and obstacle detection, implementing all UPAS functions.
Core Components
- MCU: NXP, ZLG Microelectronics, GD and others; full part number available on request
- UPAS driver IC: NCV75215 (ON)
- Level translator IC: TJA1021 (NXP)
- CAN transceiver: TJA1044 (NXP)
- LDO: Maxlinear, HTC, ON and others; full part number available on request
Key Advantages
- Strong noise immunity
- Digital bidirectional IO interface for strong noise immunity
- Wide compatibility
- Drives ultrasonic sensors from 35kHz to 90kHz, covering a wide range of devices
- High flexibility in use
- Transmit power, echo gain and receive sensitivity are all programmable for flexible use
- Discrete Fourier Transform algorithm
- A robust Discrete Fourier Transform algorithm digitally filters the obstacle echo, greatly improving noise immunity
- Adaptive drive frequency
- Measures the natural frequency of the transducer element and adapts the drive frequency accordingly, preventing sensitivity loss as the element ages
- More accurate obstacle detection in the blind zone
- Upper and lower threshold settings for transducer ringing make blind-zone obstacle detection more accurate and sensor self-test easier and more effective
- No dedicated programmer required
- The EEPROM can be programmed at the operating voltage, with no boost circuit or dedicated programmer needed
Applications
Primary applications: Ultrasonic Parking Assist System (UPAS), Automatic Parking Assist System (APAS)
Extended applications: industrial fields such as industrial robots, level measurement and distance measurement
Functional Block Diagram
