The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 18, 2005
Filed:
Oct. 08, 2003
Yoshitaka Koharagi, Oita, JP;
Masashi Nogawa, Tokyo, JP;
Yoshitaka Koharagi, Oita, JP;
Masashi Nogawa, Tokyo, JP;
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A drive circuit for LEDs or other light-emitting elements with which the influence of the changes in temperature or power supply voltage and the element variations can be restrained in order to output a pulse current with a constant level. When n-type MOS transistoris on, power is supplied from switching power supplyto the LED, and the current of LED is detected by resistor. The error signal Serr between said detection signal Sfb and setpoint signal Sref is generated by error signal generating unitand is averaged by signal holding unit. The power supplied to the LED is controlled corresponding to the averaged error signal SerrA. When n-type MOS transistoris turned off from the on state, the power supplied to the LED is stopped, and error signal SerrA is held in signal holding unit. When n-type MOS transistoris turned on from the off state, the averaging of error signal Serr is started with the signal level of the held error signal SerrA used as the initial level.