Solving Precision Timing Challenges in ADAS Systems

Precision timekeeping

Precision timing provides the heartbeat for the computing and networking components that make up Advanced Driver Assistance Systems (ADAS). The right timing solution helps drivers avoid collisions and improves safety in modern vehicles.

In this blog post, we will discuss the critical role that timing plays in ADAS.

ADAS and Timing Functions in Modern Vehicles

Most modern vehicles incorporate standard ADAS features such as pedestrian detection and avoidance, lane departure warning and correction, traffic sign recognition, automatic emergency braking, and blind spot detection. To support these advanced features, vehicles have evolved into mobile data centers. They utilize high-speed Ethernet to interconnect multiple sensors, electronic control units (ECUs), and communication gateways.

As modern vehicles become more complex, more precise timing components are needed to support these features. More sensors require more oscillators. High-speed PCIe® and Ethernet networks require more high-speed clocks. More multi-output clocks enable more computation. Implementing these enhanced safety features drives the need for increased timing content within the vehicle.

Highly assisted/autonomous driving vehicle computers

In modern vehicles, the ADAS ECU is the heart of these mobile data centers. This complex computer processes sensor and vehicle position inputs, calculates driving instructions and sends control commands to the engine, steering, braking and other functions. The central ECU is essentially the brain of the vehicle.

Components in the ECU are linked via high-speed PCIe switching, an ideal interface for critical high-bandwidth and ultra-low latency computing requirements. To connect to peripherals and other ECUs, the ECU is connected via an in-vehicle Ethernet network. Ethernet provides high-speed communications with less wiring, reducing cost and weight. PCIe, Ethernet, and other technologies all require high-frequency, low-jitter differential clock signals. In the representative ECU design above, there are fifteen different high-speed clocks.

Precision Clock Solutions

The precision clocks needed for these advanced designs have stringent requirements:

High clock frequency

Low jitter

Differential output

AEC Q100 qualified

Robust performance in high shock and vibration environments

Wide temperature range

Our DSA series of MEMS oscillators are ideal automotive timing solutions. They are small, down to 1.6 × 1.2 mm for CMOS and 2.5 × 2.0 mm for differential. They are rugged, able to withstand 50,000G shock and 70G vibration. They are very stable, maintaining ±125 ppm frequency accuracy over a wide temperature range of -20°C to 55°C. They are very flexible — configurable to any frequency output, and multiple frequencies for multi-output devices.