The Industry’s First* Speech Synthesis ICs Dedicated for AVAS (Acoustic Vehicle Alerting System) in xEVs

The ROHM group company LAPIS Technology has developed the industry’s first speech synthesis ICs – ML22120xx series (ML22120TB, ML22120GP) – designed for AVAS in xEVs (electric vehicles).

In order to achieve a carbon neutral (decarbonized) society, the number of hybrid and electric vehicles that silently operate on motor power continues to increase – prompting AVAS regulations to be enacted requiring warning sound to be emitted to alert pedestrians of their approach. However, when generating warning sound using an MCU, the pitch and volume must be smoothly controlled and characteristics adjusted to match the vehicle geometry. This increases MCU software development load requiring verification with other software processes inside the MCU. In response, LAPIS Technology released new products that contribute to reducing the burden of AVAS development by leveraging experience and technology with speech synthesis ICs. The aim: achieving a high-fidelity sound using a novel hardware-based configuration.

The ML22120TB and the ML22120GP integrate hardware functions that include a warning sound generator, fader, and equalizer. Unlike MCU-based designs, the hardware configuration eliminates the need for software validation – significantly 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 system of new ICs can be controlled by simple commands, allowing warning sound to be started in less than one-tenth the time of conventional MCU-generated systems. An included fault detection function detects both erroneous communication with the main controller and erroneous oscillation caused by external components – contributing to vehicle reliability.