Design of multi-channel LED constant current driver in radiometric calibration light source

In order to deal with the influence of the current stability controllability of LED array in integrating sphere radiometric calibration light source system on the spectrum matching degree at the opening of integrating sphere, a multi-channel, high-precision and high-stability LED current driving circuit was designed. This circuit was a voltage controlled constant current driving circuit, which can realize the linear control of LED array driving current by means of analog dimming. It took FPGA as the control core, read and wrote the AD5371 chip register through SPI interface, and realized high precision control of LED driving current through AD5371 digital-to-analog conversion circuit. The temperature control of LED array was realized based on circulating liquid refrigeration equipment and sink refrigeration base. The experimental results show that the current of LED array can be continuously and linearly adjustable in the range of 0-1 050 mA, and the current adjustment accuracy can reach 0.14% of the range. When the LED lamp holder temperature is controlled at 10 ℃, the LED output light spectral stability is 0.2%.