ASIL-rated camera power protector protects your vehicle camera

These days, your eyes aren’t the only ones on the road when you’re driving. Modern vehicles now have multiple cameras that, combined with other advanced sensors like radar and lidar, support safety features like Advanced Driver Assistance Systems (ADAS). The fusion of these sensors detects blind spots, pedestrians, streets, etc… and even guides the vehicle to park itself. For example, some of today’s semi-autonomous cars have 8 to 12 cameras that provide 360-degree surround view for parking assistance and 250 meters of forward vision for collision avoidance. These cameras can be paired with ultrasonic sensors and forward-facing radar to provide an even wider field of view.

According to a report by Research and Markets, the global automotive camera market is expected to reach approximately $7 billion by 500 million, with a compound annual growth rate of 3.2018% from 2023 to 24. Researchers cite demand for ADAS and government mandates for rear-view backup cameras in North America and Europe as key drivers of this growth. In addition, cameras are beginning to replace traditional side-view mirrors in some cars, and emerging driver monitoring systems rely on cameras to assess conditions such as drowsiness or distraction. The shift to higher safety standards will only continue to drive demand for cameras.

Given that these automotive cameras play such a critical role in safety, it’s imperative that they are powered correctly and operate reliably. You also need to consider compliance with Automotive Safety Integrity Levels (ASILs). ASILs classify the inherent safety risks in automotive systems and are an important part of compliance with ISO 26262, which provides the international standard for safety-critical automotive components.

Balancing power and protection needs

There are several power management schemes for automotive cameras, and typically the path is from the car battery providing power to the remote camera itself. Let’s assume you have a 12V car battery and several cameras that can be powered via coaxial cable. Because the voltage swing between the battery and the cable is large (typically 8V-10V, 0.3A per camera), you need to consider various constraints associated with powering the coaxial system. You need a buck-boost converter to adjust the different voltages, especially during start-stop and cold-crank conditions. However, you still need to provide some isolation for fault conditions such as overcurrent, short to ground, and short to battery, all of which can cause damage that affects the safety of the driver and passengers. To do this, you may need to develop additional hardware and software for system monitoring and/or use multiple discrete devices depending on the number of cameras in the system.

Even better, you can choose a highly integrated camera power protector IC for your automotive camera module. Such a device enables you to minimize the fault mitigation circuit by tightly controlling the maximum current of each channel. You can also isolate all faults on each camera from a single power supply and other cameras. The ideal protector IC can also communicate with the camera via I2C.

The camera protector can be part of a fused electrical control unit (ECU) for the camera system. A buck-boost converter will connect to the car battery and provide DC power to the remote camera through the camera protector, AC blocking coil, and coaxial cable. A four-channel deserializer will connect the microprocessor to the remote camera through a set of AC coupling capacitors and the same coaxial cable. Each remote camera will be managed by an automotive power management IC (PMIC), serializer, and image sensor. Figure 2 depicts this architecture.

Figure 2. Power management architecture for an automotive camera system.

The industry's only ASIL-rated camera protector

Maxim’s MAX20087 provides an example of a camera protector IC that can be plugged into a remote camera system. It is the industry’s only ASIL-rated camera protector (compliant with ASIL B to ASIL D) with integrated I2C-based diagnostics. As a dual/quad device, it provides two or four 20mA protection switches in a 600mm x 4mm, 4-pin TQFN. A single MAX20087 supports eight cameras simultaneously, while two devices connected in parallel on the same bus support <> cameras. The device protects each output individually from short-to-battery, short-to-ground, and overcurrent conditions. An integrated <>-bit analog-to-digital converter (ADC) monitors current, voltage, and power readings as required for ASIL compliance.

The MAX20087 integrates features that save you from having to use more discrete components. For example, because the device prevents battery shorts from feeding back into the power rail, there is no need to add reverse-blocking diodes on each channel. Evaluate the MAX20087 for your next car camera design by purchasing the MAX20087EVKIT evaluation kit, which can work as a standalone protector or connect to a controller via an I.2C interface for advanced control and diagnostics.

To complete the power management architecture of a camera system, Maxim offers a variety of automotive power ICs. For example, these automotive PMICs can support remote cameras:

The MAX25249 and MAX25249B quad-output micro PMICs are the industry's smallest solutions for automotive cameras with precision monitoring capabilities. These devices integrate three DC-DC converters and a high-PSRR LDO in a 3.5mm x 3.5mm, 20-pin TQFN.

The MAX20049 is a flexible, compact, quad power supply with a 2.2MHz, 500mA step-down converter and dual LDOs for automotive camera modules. The two step-down converters are designed for fixed-frequency pulse-width modulation (PWM) operation with an input voltage range of 3.5V to 17V.

Given the critical role that automotive cameras play in automotive systems, ensuring your automotive cameras are properly powered and operating reliably is critical. That’s why the right automotive PMIC can make all the difference in your design.