SAN JOSE, Calif., March 17, 2020 /PRNewswire/ -- Many of today's vehicles feature multiple cameras that, combined with other advanced sensors such as radar and LiDAR, support safety features like advanced driver assistance systems (ADAS). The fusion of these sensors detects blind spots, pedestrians, street lanes, and more. Given that these car cameras play such a critical role in safety, it's imperative to ensure that they are powered properly, operate reliably, and comply with the Automotive Safety Integrity Level (ASIL).
Automotive cameras can be supported by various power management schemes, covering the path that spans from the car battery providing the power source to the remote cameras themselves. Maxim's MAX20087 camera protector IC is the industry's only ASIL-grade camera protector (complying with ASIL B through ASIL D) with integrated I2C-based diagnostics. As a dual/quad device, the MAX20087:
- Provides two or four 600mA protection switches in a 4mm x 4mm, 20-pin TQFN package
- Supports four cameras simultaneously; two of the devices in parallel on the same bus support eight cameras
- Protects each output individually from short-to-battery, short-to-ground, and overcurrent conditions
Balancing Power and Protection Needs of Car Cameras
Globally, the automotive camera market is anticipated to reach roughly $7.5 billion by 2023, with a CAGR of 24.3% from 2018 to 2023, according to a report from Research and Markets. The researchers note that demand for ADAS as well as North American and European government requirements for rearview backup cameras are key drivers of this growth. Also, cameras are starting to replace traditional side-view mirrors in some cars, and emerging driver monitoring systems rely on cameras to assess conditions like drowsiness or distraction. The move towards higher safety standards will only continue to fuel the demand for cameras.
A traditional power management architecture for automotive cameras can involve multiple chips. For example, say you've got a 12V car battery and several cameras to power over a coaxial cable. Due to the wide voltage swings between the battery and the cabling (which is typically 8V-10V at 0.3A per camera), you will need to consider various constraints related to power over coaxial systems. You'll need a buck-boost converter to adjust for the different voltages, particularly during start-stop and cold-crank conditions. But still, you'll need to provide some isolation against fault conditions such as overcurrent, short-to-ground, and short-to-battery—all of which can cause damage and, as a result, impact driver and passenger safety. For this, you may need to develop additional hardware and software for system monitoring and/or use several discrete devices, based on the number of cameras in your system.
A smaller, more effective solution would be to use a highly integrated camera power protector IC for your automotive camera module. Such a device enables you to minimize your fault mitigation circuitry by tightly controlling the maximum current per channel. You'd also be able to isolate all faults on each camera from a single power supply and from other cameras. The camera protector, such as the MAX20087, can be part of a fusion electrical control unit (ECU) for the camera system. A buck-boost converter would connect to the car battery and deliver DC power to the remote cameras through the camera protector, AC-blocking coils, and coaxial cables. A quad deserializer would connect a microprocessor to the remote cameras over a bank of AC-coupling capacitors and the same coaxial cables. Each of the remote cameras would be managed by automotive power management ICs (PMICs), the serializer, and the image sensor.
Minimizing Need for Discrete Components
With the functionality integrated into the device, the MAX20087 minimizes the need for discrete components. For example, since the device blocks short-to-battery from backfeeding to the supply rail, a reverse blocking diode isn't needed for each channel. An integrated 8-bit analog-to-digital converter (ADC) monitors current, voltage, and supply readings as required for ASIL compliance.
The MAX20087EVKIT evaluation kit, which can operate as a stand-alone protector or be connected to a controller through an I2C interface for advanced control and diagnostics, is the starting point for assessing the MAX20087. Given the critical safety role of cameras in today's cars, it's essential to ensure that they're powered properly for reliable operation.
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SOURCE Maxim Integrated Products, Inc.