Kent Robinett, Maxim Integrated
As the auto industry continues pushing development of autonomous vehicles, cars are increasingly becoming sophisticated electronic systems on wheels. Take the Ford GT—with 10 million lines of code, this car surpasses the code volume of the Boeing 787 Dreamliner by 3 million lines!
Designing these systems comes with the usual considerations around fuel efficiency, emissions rates, and horsepower, but also considerable new technical challenges:
• Integrating new functions
• Controlling platform costs
• Freeing up space and power
• Increasing the speed of data
• Meeting new safety standards
• Reducing system complexity
The challenges will also continue to evolve as the underlying technology does. However, there are some common needs across multiple design segments, and these can all be addressed by high-performance analog solutions. This article will Let’s examine two critical—and particularly electronics-heavy—automotive applications: the advanced driver assistance system (ADAS) and the infotainment system.
Integrating multiple cameras, sensors, and sophisticated image/video processing algorithms, an ADAS system automates safety-critical capabilities like lane departure warnings, collision avoidance, and blind-spot detection. For infotainment systems, with their rich displays, navigation features, and informational messages, an effective power management strategy, and a communications-centric architecture are important. Both of these systems must complement each other while preventing dangerous situations like driver distraction.
ADAS: delivering real-time driver assistance
Cameras located at multiple points throughout a vehicle are central to an ADAS system. The video feed collected must be synchronized and processed quickly so that the ADAS system can react and respond accurately and promptly. Many GPUs and SoCs don’t have enough interface pins to take in all of this visual data. Addressing this calls for a high speed camera data aggregator.
A data compression-free solution such as Maxim’s MAX9286 provides an example. This quad-channel 1.5Gbps deserializer can synchronize video streams from four cameras while simultaneously powering each camera over the same coax cable. Using this deserializer eliminates the FPGA traditionally used to aggregate camera input data, lowering system cost, and improving performance by reducing latency in the system.
High-speed video data transfer is critical to the effectiveness of an ADAS system. For this, the camera signal must be connected to the ADAS console via high-speed, robust serial communications links that enable real-time driver assistance and safety functions.
Serializer/deserializer (SerDes) technology provides the low cost that automakers want, along with low latency, high bandwidth, and high video quality (even under challenging environmental conditions like low light or bad weather). Their architectures tend to be relatively simple, since they are transmitting uncompressed video directly from the camera sensor to the ADAS ECU. Based on these advantages, SerDes technology is considered a better option than Ethernet for automotive video applications.
3Gbit multimedia serial link (GMSL) SerDes line drivers and receivers are designed for applications like ADAS (see Figure 1). GMSL devices offer a wide range of bandwidths and support audio, video, and control communications. They also support differential or coaxial transmission media that meet the unique requirements for electromagnetic compatibility (EMC), electrostatic discharge (ESD), and power consumption.
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Figure 1: Maxim’s GMSL SerDes chipsets can be used to connect head-unit video data to rear-seat entertainment consoles.
For example, GMSL SerDes technology is compression free, drives 15 meters of coax or STP cabling, provides Power over Coax capability, and, compared to Ethernet, delivers:
• 10X faster data rates
• 50% lower cabling costs
• Better EMC
• High-bandwidth digital content protection (HDCP)
Infotainment: power management considerations
Infotainment systems manage video and audio signals, displaying everything from the vehicle’s operating status to external driving information. New features in the systems are resulting in more ports, more processors and—no surprise—more power. That’s why an efficient power management strategy is essential for infotainment applications.
Key considerations include:
• High functional integration
• High current integration
• Small form factor
• High efficiency
• Low standby power
To meet these needs, power management ICs need to provide high switching frequencies, which help minimize the form factor. It’s also important that these ICs keep electromagnetic interference (EMI) as low as possible. Such ICs are commonly placed in the radio head unit (RHU) and entertainment control modules of the infotainment system, attached directly to the main battery.
As a result, power management ICs should, through the vehicle’s lifespan, be equipped to handle high input voltages (generally above 36V) and to reliably survive load dump events. Maxim offers high-voltage and low-voltage step-down switching regulators as well as linear regulators that provide power management for infotainment systems. All of these components are designed for automotive requirements and are automotive qualified.
Enhancing the In-vehicle experience
There are many other parts of an infotainment system that can benefit from analog technology. One of the most visible parts of the system is its liquid crystal display (LCD) on the vehicle’s dashboard. These displays need brightness controls with a wide dimming range and must be operational in a low EMI environment. For the radio and satellite navigation components, low-noise amplifiers (LNAs) capture and process signals at the antenna. These same components also require high-integration radio, navigation, and television tuners and receivers.
High-performance analog solutions can address each of these infotainment needs. For example, the company’s display power ICs and backlight drivers meet the requirements of the automotive environment. For radio and satellite navigation components, Maxim offers LNAs with adjustable gain control capture, as well as solutions for AM/FM/DAB broadcast radio and GPS/GNSS satellite navigation.
Cars are already delivering a smartphone-like experience and this trend is expected to continue. Already, the Volkswagen e-Golf provides a connection that lets drivers access their compatible smartphone’s music, maps, messaging, and more from the dashboard.
The other side of this story is the need for drivers and passengers to charge their power-hungry portable electronic devices while in the car. Low-cost USB car chargers aren’t quite the answer because they introduce radio interference (RF) into the car. What’s needed is automotive-grade USB charging—such as host charger adapter emulators and charge detectors—that accounts for protection against short-circuiting and electrostatic discharge (ESD).
For example, Maxim’s MAX16984 is the industry’s first USB data protection switch that integrates a high-voltage, feedback adjustable DC-DC converter (see Figure 2). The circuit integrates a 5V automotive-grade step-down converter that can drive up to 2.5A, a USB host charger adapter emulator, and USB protection switches for automotive USB host applications. Its USB VBUS voltage is generated directly from the vehicle battery via an integrated feedback adjustment circuit. The circuit also automatically adapts to the load current, which helps compensate for cable losses.
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Figure 2: This automotive high-current step-down converter with USB protection/host charger adapter emulator integrates voltage compensation to deliver maximum charge current to portable devices.
Lighting the way toward a safer drive
According to one major OEM, its daytime running light technology helped save roughly 25,000 metric tons of CO2 during the first year of operation. Another major OEM offers LED taillight technology that goes on quickly and brightly, reacting up to 10X faster than conventional bulbs. While helping to make vehicles more noticeable on the roadways to other drivers, LED technology also is much longer-lasting than conventional lighting, shining for approximately 10,000 hours.
High-voltage, high-brightness LED drivers provide another example of analog technology that is playing an integral role in modern vehicles. For example, Maxim’s MAX16833 LED driver with integrated high-side current sense supports multiple automotive lighting applications, reducing EMI noise, reducing system bill of material (BOM) costs by supporting input voltages up to 65V, and supporting high-power applications with robust fault protection.
Car buyers are increasingly seeking vehicles that provide more sophisticated safety, reliability, and convenience features to enhance the driver and passenger experience. Automakers, in turn, are continuing to innovate, integrating more autonomous driving capabilities into their designs.
Design challenges will continue, however, as the number of electronic components as well as complexity keep growing. Today’s automotive designers have a huge opportunity to create and shape the car of the future, and high-performance analog solutions can help them get their ideas on the road.