High-power led dimming driver with multi-level current for smart street lighting system

In this paper, we present a novel high-power LED (Light Emitting Diode) driver and its dimming control using chip-level design, which is applied for white LED driving in the street lighting system. For LED dimming, we propose the multi-level current approach rather than a pulse current. which can reduce noise radiation and prolong LED lifetime. The LED current can be directly controlled by a digital binary code, to adjust the LED luminance. The chip circuit included one reference, current mirrors, current switches, digital decoder, and power driver. The prototyping chip is designed using TSMC 0.25μm high-voltage technology, and the chip area with pads is only 0.54μm². The maximum driving power is 60W as for 60V drop on LED through 1A current realized by a string of high-power LED devices. This chip is implemented with 16-step constant-current levels for LED dimming. The driving current and LED luminous flux is linearly changed in each step control from practical measurements.