Author: Miezong
When a car collides and the airbag pops out, what exactly happens behind this common occurrence?
The collision sensor detects the collision and notifies the processor, which determines the situation inside the car and opens the corresponding airbag.
The first step in deploying the airbag is from the collision sensor.
Common collision sensors include mechanical collision sensors, magnetic collision sensors, piezoelectric collision sensors, strain gauge collision sensors, pressure resistance collision sensors, and mercury switch collision sensors. Collision sensors are used to detect automotive collision signals and provide the signal to the airbag electronic control unit.
And when we talk about collision sensors, we have to mention a company I just got to know – ADI.
What is ADI?
When my friend forwarded me an activity information after being isolated for seven days due to a popup window, I was confused. What company is ADI? Why have I never heard of it?
Great sound can be invisible, and elephants can be intangible. The products of ADI, an enterprise with not much public recognition, work silently around us, supporting modern digital and networked life. I never expected that the company that I had never paid attention to had so many daily contacts in my life. Their products are used in computers, phones, headphones, cameras, signal base stations, and other products.
ADI, short for Analog Devices, is a semiconductor company founded in 1965 by two MIT graduates, Ray Stata and Matthew Lorber. As can be seen from the name “Analog Devices,” the company focuses on signal analysis and processing. ADI started by making high-performance operational amplifiers for amplifying and modifying electrical signals and has been specializing in this field from the very beginning. With the development of the digital and internet industries, ADI has also ventured into fields such as modems, SoundMax sound cards, and high-performance digital-to-analog converters.
After nearly 60 years of development, ADI’s products now include data converters, amplifiers and linear products, radio frequency (RF) ICs, power management products, micro-electro-mechanical system (MEMS) technology and other types of sensors, as well as processors in many fields, applied to almost all types of electronic devices.
Why ADI?
After reading the information about ADI, I still had questions. There’s no doubt that ADI is a great semiconductor company, but what’s its connection to our automotive media? Why invite us to attend the new product launch?
The answer lies in the development history of ADI’s MEMS product line.
As early as 1987, ADI began to develop and produce sensors based on micro-electro-mechanical system (MEMS) technology. A few years later in 1991, ADI released the first high-g MEMS accelerometer and entered the field of automotive safety airbag collision monitoring. This is the beginning of the connection between ADI MEMS products and the automotive industry.
Today, ADI’s MEMS automotive safety airbag collision sensors account for more than 50% of the market share, so there’s a chance that you’ve driven or ridden in a car that uses ADI’s sensors.
This is perhaps the reason why ADI invited us to attend the launch event for its MEMS products.
What does ADI MEMS do?
After 35 years of technological accumulation, ADI has built a comprehensive MEMS product line, including MEMS inertial devices, MEMS microphones, MEMS clocks, MEMS filters, MEMS switches and other products, covering five major motion sensing applications: acceleration, rotation, tilt angle monitoring, impact, and vibration monitoring.
At this point, you may have the same question as I do – what are the uses of acceleration, rotation, tilt, impact, and vibration in daily life?
First of all, there’s the smartwatch. By judging parameters such as acceleration and tilt, it can determine whether the wearer has fallen, and by measuring the wearer’s slight shaking and ups and downs, it can count breathing frequency.
Next comes waterproof products. Putting the sensor inside the product can activate the device through tilt or vibration, effectively avoiding the need for reinforced waterproof treatment by mechanical switches.
The most important concern is impact, which is closely related to cars. Apple’s newly released iPhone 14 and Apple Watch Series 8 have added collision detection functions, and ADI’s MEMS products can better monitor car collisions. Moreover, their three-axis accelerometers can not only determine the speed and acceleration during collisions, but also the angle, almost reproducing the situation during the collision.
ADI MEMS Products
Three products were mainly introduced in this press conference. The ultra-low-power three-axis MEMS accelerometer ADXL367, the automotive-grade low-power large-range accelerometer ADXL314, and the low-noise, low-drift, low-power three-axis MEMS accelerometer ADXL359.
The ultra-low-power ADXL367 claims to have lower self-power consumption than a button battery, and is mainly used in medical and industrial applications, including vital sign monitoring, hearing assistance, and motion measurement. For example, in the case of hearing aids, low-power accelerometers can be responsible for standby during periods of inactivity, closing other systems to save power and prevent the hearing aid from running out of battery after sitting on a table for a long time.
The automotive-grade ADXL314 with large range meets the AEC-Q100 standard and has a temperature range extending from -40°C to +125°C. With a range of 200 g, it can be used in scenarios such as tire pressure monitoring, electric vehicle battery monitoring, and collision detection. The Ministry of Industry and Information Technology has mandated that starting from January 1, 2022, newly produced passenger vehicles must be equipped with EDR event data recorders, also known as black boxes. This ADXL314 is suitable for use in EDR devices.
The ADXL359 is mainly applied in vibration environments, offering low noise, small offset drift and long-term stability. It allows for precise applications with minimal calibration requirements, such as detecting the changes in vibration when a screw comes loose in a machine and notifying for predictive maintenance.
This product release opened up a whole new world for me. Although I knew early on that the automotive industry is a complex system engineering, I did not have an intuitive understanding. But through a little three-axis accelerometer chip, the ADXL359, I gained insight into the complexity and precision of the automotive industry, where a car requires thousands of different functional chips. With advances in technology, chip functions and specifications are constantly evolving and innovating, becoming more power-efficient, accurate and durable.
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This article is a translation by ChatGPT of a Chinese report from 42HOW. If you have any questions about it, please email bd@42how.com.