High-Bandwidth Automotive Audio Bus for Software-Defined Vehicles

Analog Devices has released A2B 2.0 (ADAA245x series) to production, extending its automotive audio bus technology to support higher bandwidth, Ethernet tunneling, and scalable in-vehicle connectivity for software-defined vehicle architectures.

Evolution of Automotive Audio Connectivity
The A2B (Automotive Audio Bus) platform has been deployed across the automotive sector for over a decade, with hundreds of millions of installed nodes spanning more than 35 vehicle manufacturers. It has been primarily used in applications requiring deterministic low latency, including road-noise cancellation, hands-free communication, and distributed microphone and speaker systems.

The underlying architecture is based on a daisy-chain topology with a single main node and multiple sub-nodes. This configuration reduces wiring complexity compared to conventional point-to-point systems, enabling up to 75% reduction in cabling. The architecture also operates without software overhead, simplifying integration and reducing development time for OEMs and Tier 1 suppliers.

Requirements of Software-Defined Vehicle Architectures
The transition toward software-defined vehicle (SDV) platforms is increasing the demand for high-bandwidth, deterministic communication systems that integrate with broader in-vehicle networks. In-cabin systems such as infotainment, active noise control, and voice processing are becoming software-driven functions, requiring scalable and synchronized data transport.

This shift places new constraints on automotive audio networks, including the need for higher throughput, interoperability with Ethernet-based backbones, and predictable latency for real-time processing.

Technical Capabilities of A2B 2.0
A2B 2.0 extends the existing platform by increasing data throughput and introducing compatibility with Ethernet-based systems, while maintaining the deterministic timing behavior required for audio applications.

The system supports a fourfold increase in bandwidth, reaching up to 98.3 Mbps in full-duplex operation. This enables more complex audio configurations, including support for up to 119 upstream and 119 downstream audio channels, which is relevant for multi-zone audio, immersive sound systems, and advanced in-cabin signal processing.

Deterministic latency remains a defining characteristic, with end-to-end latency specified at 62 microseconds. This is critical for synchronization-sensitive applications such as active noise cancellation and real-time voice communication.

Integration with Automotive Data Ecosystems
A2B 2.0 introduces Ethernet data tunneling through the Open Alliance SPI (OASPI) interface, allowing audio data streams to coexist with broader vehicle network traffic. This enables integration into an automotive data ecosystem where Ethernet serves as the backbone for high-speed communication between electronic control units.

The ability to tunnel Ethernet data over the A2B network provides flexibility in system design, allowing engineers to bridge legacy audio subsystems with newer domain-based or zonal architectures without redesigning the entire network stack.

System Efficiency and Upgrade Path
The updated platform improves system efficiency through higher functional integration, reducing the need for external components and enabling up to 30% reduction in system cost. This is particularly relevant in high-volume automotive production, where component count and wiring complexity directly impact manufacturing cost and reliability.

Backward compatibility with A2B 1.0 cabling and connectors allows reuse of existing infrastructure. The ADAA245x devices can interoperate with earlier A2B networks, enabling incremental upgrades rather than full system replacement.

Application Scope
A2B 2.0 is designed for a range of automotive applications, including distributed audio systems, in-cabin communication networks, active noise control, and advanced infotainment platforms. Its combination of high bandwidth, deterministic latency, and Ethernet integration aligns with the requirements of next-generation software-defined vehicles.

The technology is now in production, supporting deployment across new vehicle programs by OEMs and Tier 1 suppliers.

Edited by an industrial journalist Sucithra Mani with AI assistance.

www.analog.com