TRIAC DIMMER COMPATIBLE LED DRIVER AND METHOD THEREOF
First Claim
1. A controller used in a LED driver, wherein the LED driver comprises a TRIAC dimmer configured to receive an AC input voltage and to generate an AC chopped voltage having a regulated conduction phase based on the AC input voltage, a rectifier configured to generate a DC chopped voltage in accordance with the AC chopped voltage, and a switching converter having at least one switch, wherein the switching converter converts the DC chopped voltage into a driving signal to drive a LED, the controller comprises:
- a dimming signal generator coupled to the TRIAC dimmer, wherein the dimming signal generator generates a dimming signal with regulated duty cycle in accordance with the AC chopped voltage;
a dimming signal processor coupled to the dimming signal generator, wherein the dimming signal processor generates a processed dimming signal in accordance with the dimming signal, and wherein the duty cycle of the processed dimming signal is a sum of a predetermined duty cycle and the duty cycle of the dimming signal; and
a switch control circuit coupled to the dimming signal processor, wherein based on the processed dimming signal and a feedback signal indicative of the current flowing through the LED, the switch control circuit generates a control signal to control the at least one switch of the switching converter.
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Abstract
The present invention provides a controller used in a TRIAC dimmer compatible LED driver and method thereof. The controller comprises a dimming signal generator, a dimming signal processor and a switch control circuit. The dimming signal generator receives an AC chopped voltage from a TRIAC dimmer and generates a dimming signal with regulated duty cycle in accordance with the AC chopped voltage. The dimming signal processor is coupled to the dimming signal generator and generates a processed dimming signal in accordance with the dimming signal. The duty cycle of the processed dimming signal is a sum of a predetermined duty cycle and the duty cycle of the dimming signal. Based on the processed dimming signal and a feedback signal indicative of the current flowing through LED, the switch control circuit generates a control signal to control at least one switch in a switching converter.
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Citations
19 Claims
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1. A controller used in a LED driver, wherein the LED driver comprises a TRIAC dimmer configured to receive an AC input voltage and to generate an AC chopped voltage having a regulated conduction phase based on the AC input voltage, a rectifier configured to generate a DC chopped voltage in accordance with the AC chopped voltage, and a switching converter having at least one switch, wherein the switching converter converts the DC chopped voltage into a driving signal to drive a LED, the controller comprises:
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a dimming signal generator coupled to the TRIAC dimmer, wherein the dimming signal generator generates a dimming signal with regulated duty cycle in accordance with the AC chopped voltage; a dimming signal processor coupled to the dimming signal generator, wherein the dimming signal processor generates a processed dimming signal in accordance with the dimming signal, and wherein the duty cycle of the processed dimming signal is a sum of a predetermined duty cycle and the duty cycle of the dimming signal; and a switch control circuit coupled to the dimming signal processor, wherein based on the processed dimming signal and a feedback signal indicative of the current flowing through the LED, the switch control circuit generates a control signal to control the at least one switch of the switching converter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A controller used in a LED driver, wherein the LED driver comprises a TRIAC dimmer configured to receive an AC input voltage and generate an AC chopped voltage having regulated conduction phase based on the AC input voltage, a rectifier configured to generate a DC chopped voltage in accordance with the AC chopped voltage, and a switching converter having at least one switch, wherein the switching converter converts the DC chopped voltage into a driving signal to drive LED, the controller comprises:
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a dimming signal generator coupled to the TRIAC dimmer, wherein the dimming signal generator generates a dimming signal with regulated duty cycle in accordance with the AC chopped voltage; a reference signal generator coupled to the dimming signal generator, wherein the reference signal generator generates a reference signal in accordance with the dimming signal, the average value of the reference signal is the difference between the product of a first constant and the duty cycle of the dimming signal, and a second constant, wherein the first constant is larger than the second constant; and a switch control circuit coupled to the reference signal generator, wherein based on the reference signal and a feedback signal indicative of the current flowing through LED, the switch control circuit generates a control signal to control the at least one switch. - View Dependent Claims (10, 11, 12, 13)
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14. A method for driving a LED, comprising:
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receiving an AC chopped voltage with regulated conduction phase from a TRIAC dimmer; rectifying the AC chopped voltage to generate a DC chopped voltage; converting the DC chopped voltage into a driving signal to drive the LED through a switching converter having at least one switch; generating a dimming signal with regulated duty cycle in accordance with the AC chopped voltage; generating a processed dimming signal in accordance with the dimming signal, wherein the duty cycle of the processed dimming signal is a sum of a predetermined duty cycle and the duty cycle of the dimming signal; generating a feedback signal indicative of the current flowing through LED; and generating a control signal based on the processed dimming signal and the feedback signal to control the at least one switch. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification