Title :
A white LED boost IC for backlight of TFTLCD based on a current-limited pulse-width modulation
Author :
Guo-Ming Sung ; You-Hsiang Lu
Author_Institution :
Dept. of Electr. Eng., Taipei Univ. of Technol., Taipei, Taiwan
Abstract :
This paper presents a boost DC-to-DC switching converter which is implemented with current-limited pulse width modulation (PWM) to drive various white LEDs in the backlight of TFTLCD. The proposed white LED boost IC consists of the bandgap reference, error amplifier, hysteresis comparator, linear ramp generator, voltage-to-current converter and driving buffer which are designed and implemented with a standard 0.35-μm 2P4M CMOS technology. Notify that the proposed bandgap reference can provide a reference voltage and a reference current, simultaneously. Besides, the white LED boost IC can eliminate sub-harmonic oscillation using a slope-compensation technique. Simulation results show that the output voltage, output current, output voltage ripple and output current ripple are 18 V, 20 mA, 5.98 mV and 41.8 μA, respectively, at a power supply of 3.3 V. The proposed white LED boost IC can drive five white LEDs with a power efficiency of 85% and a chip area of 0.89×0.92 mm2.
Keywords :
CMOS integrated circuits; DC-DC power convertors; LED displays; PWM power convertors; amplifiers; comparators (circuits); liquid crystal displays; switching convertors; 2P4M CMOS technology; TFTLCD; backlight; bandgap reference; boost DC-to-DC switching converter; current 20 mA; current 41.8 muA; current-limited PWM; driving buffer; efficiency 85 percent; error amplifier; hysteresis comparator; linear ramp generator; pulse-width modulation; reference current; reference voltage; size 0.35 mum; size 0.89 mm; size 0.92 mm; slope-compensation technique; subharmonic oscillation; voltage 18 V; voltage 3.3 V; voltage 5.98 mV; voltage-to-current converter; white LED boost IC; CMOS integrated circuits; CMOS technology; Clocks; Light emitting diodes; Low earth orbit satellites; Manganese; Switching circuits;
Conference_Titel :
Circuits and Systems (MWSCAS), 2011 IEEE 54th International Midwest Symposium on
Conference_Location :
Seoul
Print_ISBN :
978-1-61284-856-3
Electronic_ISBN :
1548-3746
DOI :
10.1109/MWSCAS.2011.6026415
