Microcontroller-controlled constant current DC-DC converter modules for driving a multi-wavelength LED array

This paper presents the design and validation of constant current DC-DC converter modules which provide constant current operation for driving an LED array that is comprised of multiple wavelength LEDs. A high-power LED-based light source can provide optical energy to test solar panels indoors. For this application, the light source, whose optical spectrum and irradiance that is similar to solar rays, is required. The light source would consist of various types of LEDs whose wavelengths and intensities are different from one another and so the power source needs to supply a specific current and voltage for each LED. The described module consists of a DC-DC converter and constant current control circuits, which are controlled by a microcontroller. Both circuits of the module set the module's output current and voltage levels by adjusting the feedback resistances of the step-down controller and the DC amplifier gain. Two resistances are configured by a digital potentiometer IC through a microcontroller. To control multiple various types of LEDs efficiently the I2C serial bus is used. Up to 128 described modules can be attached and controlled by a single microcontroller. To verify the operation and performance, a printed-circuit board prototype has been built and tested; simulation and experimental results are presented. The measurement results show that the module successfully drives a high-power LED with the constant current operation controlled by a microcontroller.