An Integrated Lighting Unit With Regulated Pulse Current Driving Technique

This paper proposes an integrated lighting unit using the regulated-pulse-current-driving technique for low-power application. On-chip/package integration of a white light-emitting diode (WLED) with a light-emitting diode (LED) driver, also named a lighting unit in this paper, may be ideal for smaller and lighter portable devices. The integrated lighting unit is connected to a pulse current driver fabricated with the complementary metal-oxide-semiconductor (CMOS) technology and a WLED on-chip integration. Such a combination would help reduce the packaging costs and the size of the device as well as increase the luminous density. Two control signals are used in the proposed driver to modulate the pulse current. One signal modulates the amplitude of the pulse current from 100 to 500 mA, and the other modulates the pulse current frequency between the ranges of 350 and 750 kHz. The dimming method and experiments on the prototype of the lighting unit have been built and measured. The active area of the designed chip is 0.64 mm × 0.56 mm in a 0.5-μm CMOS process. The resulting integrated lighting unit works well; therefore, this compact device is suitable for portable applications.