Laser driven projectors are becoming popular in specific automotive and consumer equipment, such as ADAS head-up displays for car dashboards and in portable Pico video projectors to view presentations and films and is being driven by technology advances in electronics integration, ultra-small IC packaging and light sources.
Laser projectors have a significant advantage over conventional displays using LEDs, their colour range is twice as large and its contrast ratio is much better for a crystal-clear visibility of the displayed content.
The RN5C750 and RN5C752 are four-channel laser drivers that have been developed for use in RGB or RGGB laser scanning type screens and are equipped with many functions.
They offer a full HD resolution (1080p) and 60 fps image thanks to a fast laser diode output of 200 megapixel / sec and a high output current of up to 800 mA (LD1) and 400 mA (LD2-4). The laser diode outputs can tolerate voltages up to 10V to make it possible to use laser diodes with a high forward voltage.
In addition, power control for the laser diodes is performed by automatically adjusting the power source to save power and reduce heat dissipation. These devices also contain various protection circuits such as laser diode overcurrent and short detection, thermal shutdown and photodiode overcurrent detection.
The RN5C750 has passed the AEC-Q100 (Grade 2) compatible reliability tests for automotive purposes and has a guaranteed operating temperature range from -40 to +105°C. The RN5C752 is an identical IC for consumer applications and has a temperature range from 0 to +70°C.
A special feature adopted from professional laser printers is used to deliver a high-quality output regardless of temperature. By using four additional photodiode sensors connected to the IC, it is possible to automatically detect the threshold current (Ith) and colour current (Icolor) of each channel and maintains its colour range regardless of temperature fluctuations.
