Chip and Sensor Testing
7.1 The E-Fuse
With the ongoing development of smart vehicles and electrification, compact, lightweight, smart and easy-to-install electrical fuse boxes have been developed. These so-called ‘smart fuse boxes’ utilise technologies such as SiC and MOSFET eFuses, eSwitches and LIN communication.
SiC E-Fuse from Microchip
The electrified architecture of this smart fuse box offers several advantages. These systems have a longer service life, require less wiring, contribute to reducing vehicle weight and enable intelligent power distribution within the vehicle.
Key features of the smart fuse box:
– They can measure current and voltage.
– They provide surge protection, limiting the output voltage to prevent further damage.
– They feature overcurrent protection: an eFuse can interrupt the circuit extremely quickly when the current rises well above the limit – within just 150 microseconds.
– In the event of overheating (e.g. due to overload), the eFuse automatically switches off as soon as a critical temperature is exceeded in order to protect itself.
– They block reverse current thanks to the reverse voltage generated by inductive loads.
7.2 Autonomous driving and sensors
Autonomous vehicles use a combination of sensors and processing systems to understand their surroundings and make driving decisions. The degree to which a vehicle can drive autonomously is internationally designated by the SAE autonomy levels, ranging from 0 to 5. Each level describes the division of roles between humans and machines in the driving process.
Overview of SAE levels of autonomous driving:
Level 0 – No automation:
The driver performs all driving tasks themselves. There may be warnings, such as an emergency brake warning, but the vehicle does not take control.
Number of sensors: 0–2 ultrasonic sensors or simple cameras (e.g. front camera for warning).
• Level 1 – Driving assistance:
The vehicle can take over a single task, such as adaptive cruise control or steering assistance. The driver remains responsible for all driving behaviour.
Number of sensors: 1 radar + 1 front camera (sometimes supplemented with 2–4 ultrasonic parking sensors).
• Level 2 – Partial automation:
The vehicle can steer and accelerate/brake, but the driver must actively monitor and be able to intervene immediately.
Number of sensors: 1 radar, 1 front camera, 8–12 ultrasonic sensors, 4–6 surround cameras (e.g. 360° view), sometimes lidar option.
• Level 3 – Conditional automation:
Under certain circumstances, the vehicle can drive completely autonomously. However, the driver must remain available to intervene when the system indicates this is necessary.
Number of sensors: 3–5 radars, 8–12 cameras (including DMS camera on the driver), 1–2 lidars, IMU, high-precision GPS.
• Level 4 – High automation:
The vehicle can drive autonomously in specific situations or defined areas (such as city centres or motorways) without driver intervention. No intervention is required in these zones.
Number of sensors: 3+ lidars, 6+ radars, 10–20 cameras (ambient and interior), ultrasonic sensors, IMU, redundant GPS, V2X modules.
• Level 5 – Full automation:
The vehicle drives completely autonomously under all conditions. No steering wheel, accelerator pedal or driver is required.
Number of sensors: 4–6 lidars, 6+ radars, 12–30 cameras, GPS with RTK correction, IMU, V2X, dual power supply, failover systems.
In order to drive autonomously, a vehicle uses a combination of different sensors. Cameras recognise lanes, traffic lights, pedestrians and other vehicles. Radar measures the distance and speed of objects, even in bad weather or in the dark. Lidar uses laser pulses to map a detailed 3D environment and is often used in vehicles with higher levels of autonomy. Ultrasonic sensors detect objects at close range, for example when parking. In addition, GPS and Inertial Measurement Units (IMUs) are used to accurately determine the position and movement of the vehicle. For higher levels of automation, V2X (Vehicle-to-Everything) communication also plays an important role, whereby the vehicle exchanges data with other vehicles, traffic lights and infrastructure to better anticipate traffic situations. Together, these sensor technologies form the backbone of autonomous driving functionality and are evolving as vehicle systems become increasingly intelligent and safer.
7.3 LiDAR testing
LiDAR, one of the core technologies for advanced driver assistance systems (ADAS) and autonomous driving, uses pulsed lasers to measure distances to a target with high precision. Whereas large, mechanically rotating LiDAR systems were mainly used in the past, the technology is now shifting towards more compact solid-state versions. These contain more integrated components and are smaller in size, which contributes to lower production costs.
Automotive grade LiDAR sensor from RoboSense
A DC power supply is required for testing LiDAR systems. A CV (Constant Voltage) control loop is usually used for this purpose. A well-known problem with this is that a significant current overshoot can occur during start-up. Because LiDAR systems are very sensitive to current peaks, excessive overshoot can cause irreparable damage to the laser components.
Test challenge:
As LiDAR is based on semiconductor technology, it is particularly vulnerable to inrush currents when switching on standard DC power supplies. These can permanently damage the laser.
Solution:
A DC power supply with a peak power of +/-800 Wms offers a reliable test solution. Preferably equipped with a CC/CV priority function to effectively prevent current overshoot, enabling safe and accurate operation of the LiDAR. A multi-channel setup may be interesting for simultaneous testing.
7.4 EV Chip and Sensors (MEMS)
MEMS (Micro-Electro-Mechanical Systems) sensors play a crucial role in the operation and safety of modern electric vehicles. Thanks to their compact size, low energy consumption and high accuracy, they are ideal for integration into various electronic systems in the vehicle. In an EV, MEMS sensors are used for vehicle stability, navigation, safety, driver assistance systems (ADAS) and battery management, among other things.
Melexis MEMS sensor for EV thermal management
MEMS sensors can be divided into five main types, each with their specific applications:
Acceleration sensors (accelerometers) measure acceleration in one or more directions. They are indispensable for systems such as airbag activation, electronic stability control (ESC) and driving behaviour analysis. They also ensure that position determination remains possible within the navigation system, even when the GPS signal is lost.
Gyroscopes measure the rotational speed around one or more axes. In combination with accelerometers, they provide accurate data for navigation and are used for stability monitoring, automatic lane assistance and autonomous driving functions.
Pressure sensors detect pressure changes and are used in systems such as tyre pressure monitoring systems (TPMS), hydraulic brake boosters and battery management systems (for monitoring pressure in battery cells or cooling systems).
Acoustic MEMS, such as microphones, are used for voice recognition, communication with the driver, and sometimes also for detecting abnormal noises or vibrations in critical components such as electric motors.
Finally, there are MEMS-based temperature sensors, which contribute to the thermal management of batteries, powertrain components and the vehicle’s interior climate.
Together, these MEMS sensors form the nervous system of the modern EV. They support not only basic functionalities, but also advanced features such as semi-autonomous driving, fault detection and energy saving, making them an essential part of the vehicle architecture of the future.
Bosch MEMS module with sensor and evaluation circuit (ASIC)
Testing
Test methods for MEMS in EV applications focus primarily on functional performance, robustness and stability under dynamic conditions.
The MEMS sensors in an electric vehicle undergo a series of intensive tests to ensure that they function correctly within the vehicle’s electrical system and can withstand the harsh electrical and thermal environment of an EV. During driving and charging, these sensors are exposed to sudden current surges, high switching frequencies, and rapid voltage changes, especially when powerful electrical components such as the motor controller, DC/DC converters, or charging system switch.
That is why MEMS sensors are tested for their response under high current and high speed conditions. For example, an acceleration sensor must continue to function reliably during abrupt accelerations or emergency manoeuvres in which large amounts of current flow through the vehicle. Gyroscopes and temperature sensors must also remain accurate under thermal stress and electromagnetic interference, which can be caused by regenerative braking or DC fast charging, for example.
The test setups simulate these extreme conditions using Source Measure Units (SMUs) that can simulate rapid voltage and current changes. In addition, electrical influences such as noise and overshoot are generated in a controlled manner to assess whether the MEMS components continue to function correctly without erroneous measurements or damage.
Furthermore, durability and lifetime tests are conducted, during which sensors remain active for thousands of hours under typical EV loads. The combination of mechanical vibrations, temperature cycles, and electrical stress is used to detect early defects.
The test procedures are crucial to ensure that the MEMS sensors continue to operate reliably throughout the entire service life of the vehicle, even under the most demanding conditions.
