A multi-channel high precision current matching LED Driver for intelligent dimming

Abstract

In this paper, a LED Driver with precise current matching is proposed. Through the help of artful layout schemes, the accurately matched LED currents are achieved with high tolerance to process, temperature and voltage (PVT) variations. Even with high voltage MOSFETs, the maximum current mismatch among LED channels is measured to be merely -0.385%~0.372% which is almost one-order better than those of the conventional ones. The temperature coefficient of this circuit is as low as 20ppm/°C over -40°C ~125°C range for 20mA LED driving current. This circuit was fabricated in TSMC 0.25μm 1P3M process with a chip size of 1.15*1.9mm2.