Design of Efficient White LED Driver
Date Issued
2007
Date
2007
Author(s)
Liu, Sheng-Hsin
DOI
en-US
Abstract
As the fast growing of today’s portable consumer electronics, the reduction of power consumption or improvement of power efficiency has become an important subject for the power IC designer. This thesis presents the design and implementation of efficient white LED driver. This white LED driver includes a switched-capacitor voltage converter, high PSRR low dropout linear regulator and a brightness control circuit. Since the switched-capacitor contains three types of fractional gain to boost the supply voltage, the lifetime of battery can be extended. Moreover, a technique of clock boosting is utilized to alleviate the charge loss in the duration of switching for the switched-capacitor circuit and then the power efficiency can be improved. The high PSRR low dropout linear regulator is designed to inhibit the noise from the output of switched-capacitor voltage converter and regulate the output voltage of white LED driver. Therefore, the output ripple voltage can be reduced significantly. The brightness control circuit is used to adjust the forward current of each LED by setting the external resistors and control signal.
The overall circuits included in the white LED driver are simulated by tsmc 2P4M 0.35μm 5V CMOS process. The white LED driver provides the topology of parallel connection for each LED, which has the maximum current rating 20mA at its forward voltage 3.6V. The amount of connected LEDs is flexible for different applications and the maximum is five.
Subjects
交換電容式電壓轉換器
供應電源排斥比
低壓降線性電壓穩壓器
switched-capacitor voltage converter
PSRR
LDO
Type
thesis
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