1.35MP CMOS image sensor enhances automotive safety

22nd October 2014

Melexis

Nat Bowers

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Datasheet

Designed for automotive safety applications, the MLX75421 Blackbird has been introduced by Melexis. This High Dynamic Range (HDR) image sensor provides an extensive set of on-chip functional safety (ASIL) support functions, making it suitable for automatic emergency braking, electronic mirrors/camera monitor systems, autonomous evasive steering and next-gen viewing applications.

Featuring a 1/3” optical format with a 1344x1008px resolution, the image sensor runs fully automatically in HDR mode without the need for a companion chip. A four stabilised kneepoint HDR response curve provides up to 125dB of HDR inside every frame. The HDR full frame rate is 45fps, although, 60fps is possible when capturing image data from 800 rows, making the MLX75421 Blackbird compatible with 720p applications.

Dark leakage of less than 5 electrons/s at 25°C and dark temporal noise of less than 4.4 electrons for a 1/30s exposure time enable low noise operation. This results in an SNR1 illuminance value of 0.005lx for light with a wavelength of 535nm over the same exposure time. The MLX75421 Blackbird operates over a temperature range from -40 to +115°C, providing temperature robustness for automotive applications.

Cliff De Locht, Product Marketing Manager, Melexis, comments: “Cost-effective support for ASIL systems was a key design specification from the start. For Blackbird’s functional safety design, we drew the company’s internally available functional safety expertise as Melexis already manufactures other ASIL ready sensors. This resulted in an impressively smart functional safety design and gives us a head start in targeting safety systems like automatic emergency braking and other autonomous functions for driverless cars."

Aimed at a cost-effective implementation of ASIL systems, the MLX75421 Blackbird’s ASIL support functions enable it to generate an embedded ‘frame valid’ flag for every frame based on intensive run-time self-testing.

“For almost every automotive camera function, car manufacturers and their technology partners are telling us that they need markedly improved low-light performance on what is currently available from image sensor suppliers. Drivers who have earlier generation camera systems in their cars generally want to see more at night. Also upcoming NCAP 5-star car ratings are expected to include night conditions for pedestrian and bicycle detection. That’s why we made camera sensitivity and low noise design paramount when developing the Blackbird series. The result is best in class low-light and HDR behaviour," added De Locht.

The MLX75421 Blackbird image sensor is available in monochrome, RCCC, colour RGBG and colour RGBC versions.