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A multiple-output switched-capacitor DC–DC converter for individual brightness control of RGB LEDs with time-interleaved control and output current regulation

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Abstract

In this paper, an integrated multiple-output switched-capacitor (SC) converter with time-interleaved control and output current regulation is presented. The SC converter can reduce the number of passive components and die areas by using only one flying capacitor and by sharing active devices. The proposed converter has three outputs for individual brightness control of red–green–blue (RGB) LEDs. Each output directly regulates the current due to the V–I characteristics of LEDs, which are sensitive to PVT variations. In the proposed converter, the current-sensing technique is used to control the output current, instead of current-regulation elements (resistors or linear regulators). Additionally, in order to reduce the active area, three outputs share one current-sensing circuit. In order to improve the sensing accuracy, bias current compensation is applied to a current-sensing circuit. The proposed converter has been fabricated with a CMOS 0.13-μm 1P6M CMOS process. The input voltage range of the converter is 2.5–3.3 V, and the switching frequency is 200 kHz. The peak power efficiency reaches 71.8 % at V IN =2.5 V, I LED1 = 10 mA, I LED2 = 18 mA, and I LED3 = 20 mA. The current variations of individual outputs at different supply voltages are less than 0.89, 0.72, and 0.63 %, respectively.

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Acknowledgments

This research was supported in part by the Ministry of Knowledge Economy, Korea, under the University ITRC support program supervised by the National IT Industry Promotion Agency (NIPA-2013-H0301-13-1007), and supported in part by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2013R1A1A2011973).

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  1. Department of Electrical Engineering, Hanyang University, Ansan, 426-791, Korea

    Youngkook Ahn, Inho Jeon & Jeongjin Roh

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  1. Youngkook Ahn
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  2. Inho Jeon
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Correspondence to Jeongjin Roh.

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Ahn, Y., Jeon, I. & Roh, J. A multiple-output switched-capacitor DC–DC converter for individual brightness control of RGB LEDs with time-interleaved control and output current regulation. Analog Integr Circ Sig Process 79, 345–354 (2014). https://doi.org/10.1007/s10470-014-0269-1

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