Hybrid and electric cars are difficult to be heard by pedestrians at a very low speeds

Designed to emit vehicle warning sounds and alert pedestrians to the presence of electric drive vehicles, Acoustic Vehicle Alerting Systems (AVAS) must maintain a continuous noise level of at least 56 dBA (within 2 meters) if the car is going 20 km/h (12 mph) or slower, and a maximum of 75 dBA for all new quiet electric and hybrid vehicles registered from July 2021.

The solution is built around two SPC58 automotive microcontrollers; the first acts as a domain controller, while the second one stores the recorded WAV files as well as monitors and controls the AEC-Q100 qualified FDA903D Class-D power amplifiers used to generate the required AVAS sounds.

Benefits of ST’s cost-effective stereo AVAS solution

Our AVAS solution lets car manufacturers and OEMs offer customized sounds thanks to a flexible sound generation solution able to simulate engine sounds using WAV audio files. To ensure the warning sounds are heard over the vehicle's entire length, even for long vehicles, ST's solution includes two audio amplifiers in a Stereo configuration, with both speakers playing the same mono sound or two different (stereo) sounds to improve pedestrian awareness of the car with an accurate perception of car’s distance and position.

We propose using an SPC58EC80E5 automotive MCU as the domain controller. This dual-core 32-bit Power Architecture MCU will manage the audio zone consisting of a single-core SPC582B60E1 automotive MCU that contains the recorded WAV files to be played and drives the two single-bridge FDA903D power amplifiers that deliver the audio output to the speakers.