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Patent Searching and Data


Title:
DRIVE CIRCUIT
Document Type and Number:
Japanese Patent JP2005310854
Kind Code:
A
Abstract:

To enhance the efficiency of a drive circuit for driving a light emitting device.

The drive circuit for driving a white LED 20 comprises a charge-transfer device, a capacitor coupled to the charge-transfer device, and a step-up circuit 50 for transforming a power supply voltage Vdd inputted to the charge-transfer device to 1.5Vdd in accordance with a clock CLK applied to the capacitor. A drive current from the set-up circuit 50 is supplied to the white LED 20. Moreover, a pulse detection circuit 40 for detecting a pulse BP for brightness adjustment and a switching circuit 30 for a drive current ID are provided in order to control the drive current ID flowing in the white LED 20, and adjust the brightness of the white LED 20. Additionally, a frequency divider 60 is provided that is capable of switching frequencies in such a way that the frequency of the clock CLK is reduced correspondingly when the drive current ID is reduced due to the brightness adjustment by the switching circuit 30.


Inventors:
Kawai, Shuhei
Application Number:
JP2004000122435
Publication Date:
November 04, 2005
Filing Date:
April 19, 2004
Export Citation:
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Assignee:
SANYO ELECTRIC CO LTD
International Classes:
H01L33/00; H01J40/14; H03K3/42; H03K19/094; H02M3/07; (IPC1-7): H01L33/00
Attorney, Agent or Firm:
須藤 克彦