Magesh Kannan PARTHASARATHY, Nagarajan GANESAN

A novel single-inductor eight-channel light-emitting diode driver for low power display backlight applications

A novel decoder-based single-inductor eight-channel light-emitting diode (LED) driver circuit for low powerdisplay backlight applications has been proposed. Uniform brightness in the display provides better picture clarity, whichcan be achieved by providing uniform DC currents to all channels in the backlight arrangement. Existing systems useindividual current regulators for each channel, which fails to provide uniform current to individual channels. Instead,uniform current is provided to all eight channels in the proposed system as the same current is distributed to all channelsusing time-multiplexing by a 3 × 8 decoder and a 3-bit binary up-counter. A digital pulse width modulator is usedin the existing system, which has unwanted switching activities and electromagnetic interference (EMI). Unwantedswitching activities and EMI are completely eliminated in the proposed system by applying a novel switching technique.The proposed LED driver is designed and implemented using the 180-nm CMOS process. Each channel is designed toconduct 300 mA of current through it when the supply is 12 V. The proposed LED driver consumes total power of 8.746W at 27 ${}^◦C$ while the peak power efficiency is 96.26%. The minimum current balancing error of the proposed LEDdriver is 0.019%, whereas it is 0.12% for the existing system. The existing method exhibits an average current balancingerror of 2.04% whereas the proposed technique exhibits 1.33% as the average current balancing error, which is 34.82%less than the existing system.

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