ROHM Semiconductor

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


Optimized hardware configuration and GUI software significantly reduce development load

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.





Product Lineup


Application Examples

Acoustic Vehicle Alerting System (AVAS), external vehicle alert sounds (sliding door open/close, charging completion), etc.


Click on the link below for more information on the new speech synthesis ICs.

Evaluation Board, GUI Software Information

An evaluation board along with a Sound Device Control Kit [SDCK3] that includes dedicated GUI software are available, enabling easy evaluation of everything from sound generation to correction and trial listening of alert sounds.


Online Sales Information

Online Distributors: DigiKey, Mouser and Farnell

Pricing: $7.0/unit (samples, excluding tax)

Availability: Now (OEM quantities)

The products and evaluation board will be offered at other online distributors as they become available.

Product Information

Applicable Part No: ML22120TBZ0B-MX

Evaluation Board Part No: RB-D22120TB32 – Online Distributors: DigiKey, Mouser and Farnell

Sound Device Control Kit Part No: SDCK3 – Online Distributors: DigiKey, Mouser and Farnell


GUI (Graphical User Interface)

A function that displays graphics and images on the computer screen to enable easy operation using a mouse or touch panel.

AVAS Regulation

The mandatory implementation of Acoustic Vehicle Alerting System (AVAS) was adopted by the United Nations Economic Commission for Europe’s (UN/ECE) World Forum for Harmonization of Vehicle Regulations (WP29) under UN Regulation No. 138 on Quiet Road Transport Vehicles. This regulation stipulates the volume of warning sound for approaching vehicles and frequencies at certain vehicle speeds.

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