The ROHM group company LAPIS Technology has developed the industry's first speech synthesis ICs – the ML22120xx series (ML22120TB, ML22120GP) – designed for AVAS in xEVs.
To achieve a carbon-neutral society, the number of HEVs and EVs that silently function on motor power continues to grow – prompting AVAS regulations to be enacted that need a warning sound to alert pedestrians of their approach. However, when generating a warning sound utilising an MCU, the pitch and volume must be smoothly controlled and characteristics adjusted to match the vehicle geometry. This increases the MCU software development load, needing verification with other software processes inside the MCU. In response, the company released new products that contribute to lowering the burden of AVAS development by using experience and technology with speech synthesis ICs. The aim is to achieve a high-fidelity sound using a novel hardware-based configuration.
The ICs integrate hardware functions incorporating warning sound generators, faders, and equalisers. Unlike MCU-based designs, the hardware configuration eradicates the necessity for software validation – greatly reducing development time. At the same time, dedicated GUI software makes it easy to comply with regulations for volume and frequency characteristics required for AVAS.
The new ICs can be controlled by simple commands, allowing warning sounds to be started in less than one-tenth of the time of conventional MCU-generated systems. An included fault detection function detects erroneous communication with the main controller and erroneous oscillation caused by external components – contributing to vehicle reliability.
Typical application examples include AVAS and external vehicle alert sounds, including sliding door open/close, charging completion, etc.