Time-of-flight sensing builds 3D images in difficult environments

January 19, 2017 // By Graham Prophet
Melexis (Tessenderlo, Belgium) has added a chipset and its evaluation kit for time‐of‐flight (ToF) 3D vision solutions for the most challenging environments. The ToF sensor solution claims advanced sunlight robustness and extended temperature range, enabling fast design of compact and robust 3D ToF cameras.

A complete ToF sensor and control solution, the chipset supports QVGA (320 x 240 pixel) resolution and offers sunlight robustness with up to -40°C to +105°C temperature range operation. The Melexis chipset brings together the company’s MLX75023 1/3-inch optical format ToF sensor and the MLX75123, a companion IC that controls the sensor and illumination unit and delivers data to a host processor. Together the devices can minimize the component count and reduce the size of 3D ToF cameras. Designed for maximum flexibility, the modular EVK75123 QVGA evaluation kit combines a sensor board featuring the chipset, an illumination module, an interface board and a processor module.


The MLX75023 sensor has QVGA resolution and a high level of background light rejection capabilities of up to 120 klux. This IC can provide raw data output in less than 1.5 msec, aiding its capacity to track rapid movement. The MLX75123 control chip has 12‐bit parallel camera interface and I ²C connectivity and four integrated high-speed ADCs. Integrated functions include diagnostics and support for region‐of‐interest, configurable timing, image flipping, statistics and switching modulation frequencies.

As the MLX75023 and MLX75123 have respective footprints of 7 x 7 mm and 6.6 x 5.5 mm, they require minimal board real estate. Use the pairing, Melexis suggests, in automotive, surveillance and smart buildings, as well as industrial applications including machine vision, robotics and factory automation. High-temperature capabilities mean that the need for active cooling can be minimized.


Consisting of four vertically stacked PCBs - sensor board, illumination board, interface board and processor board - the EVK75123 evaluation kit has an 80 x 50 x 35 mm form factor and features an NXP i.MX6 multi-core processor. Its illumination unit has four VCSELs, with a choice of either 60° field-of-view (FoV) or a wider 110° option for acquiring imaging data from a broader area. With its modular construction, engineers can choose which elements are needed. For example, they