First ASIL camera power protection chip

First ASIL camera power protection chip

New Products |
By Nick Flaherty

Maxim has launched the industry’s first ASIL-grade power protection device for cameras in vehicles.

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. With AEC-Q100 qualification, the chip operates from -40°C to +125°C.

The chip supports four cameras simultaneously, so two of the devices in parallel on the same bus support eight cameras. This protects each output individually from short-to-battery, short-to-ground, and overcurrent conditions.

With 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.

If several cameras are powered by a 12V battery over a coax cable, the wide voltage swings between the battery and the cabling (which is typically 8V-10V at 0.3A per camera) means designer need to various additional devices. This includes a buck-boost converter to adjust for the different voltages, particularly during start-stop and cold-crank conditions as well as isolation against fault conditions such as overcurrent, short-to-ground, and short-to-battery. 

Using a highly integrated camera power protector IC for your automotive camera module minimises the fault mitigation circuitry by tightly controlling the maximum current per channel and isolates all faults on each camera from a single power supply and from other cameras. The MAX20087 camera protector 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 then 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.

As the MAX20087 blocks short-to-battery from backfeeding to the supply rail, a reverse blocking diode isn’t needed for each channel. An integrated 8-bit analogue-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.

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