Dimmable LED driver and driving method
First Claim
1. A dimmable light-emitting diode (LED) driver, comprising:
- a) a silicon-controlled rectifier (SCR), an electronic transformer, and a rectifier bridge configured to convert an AC voltage to a DC voltage signal;
b) a power stage circuit configured to receive said DC voltage signal, and to output a constant current to drive an LED load, wherein said power stage circuit comprises first and second power stage circuits, wherein said first power stage circuit is configured to receive said DC voltage signal, and to generate a first output voltage to said second power stage;
c) an input current control circuit configured to receive an input current of said first power stage circuit and said first output voltage, and to generate a first control signal to control said input current as a square wave signal during an on time of said SCR, and said input current is maintained as substantially zero during an off time of said SCR;
d) wherein, during said on time of said SCR, a peak of said input current is a substantially constant value that satisfies a minimum load current requirement of said electronic transformer, and a valley of said input current is substantially zero; and
e) wherein said LED driver is configured to drive said LED load in accordance with said input current and said first output voltage.
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Accused Products
Abstract
Disclosed are dimmable LED driver circuits and methods. A dimmable LED driver can include: an SCR, an electronic transformer, and a rectifier bridge to convert an AC voltage to a DC voltage signal; a power stage circuit that receives the DC voltage signal, and outputs a constant current to drive an LED load, where the power stage circuit includes first and second power stage circuits, the first power stage circuit receiving the DC voltage signal, and generating a first output voltage to the second power stage; and an input current control circuit that receives an input current of the first power stage circuit and the first output voltage, and generates a first control signal to control the input current as a square wave signal during an on time of the SCR, and the input current is substantially zero during an off time of the SCR.
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Citations
15 Claims
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1. A dimmable light-emitting diode (LED) driver, comprising:
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a) a silicon-controlled rectifier (SCR), an electronic transformer, and a rectifier bridge configured to convert an AC voltage to a DC voltage signal; b) a power stage circuit configured to receive said DC voltage signal, and to output a constant current to drive an LED load, wherein said power stage circuit comprises first and second power stage circuits, wherein said first power stage circuit is configured to receive said DC voltage signal, and to generate a first output voltage to said second power stage; c) an input current control circuit configured to receive an input current of said first power stage circuit and said first output voltage, and to generate a first control signal to control said input current as a square wave signal during an on time of said SCR, and said input current is maintained as substantially zero during an off time of said SCR; d) wherein, during said on time of said SCR, a peak of said input current is a substantially constant value that satisfies a minimum load current requirement of said electronic transformer, and a valley of said input current is substantially zero; and e) wherein said LED driver is configured to drive said LED load in accordance with said input current and said first output voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of driving a dimmable light-emitting diode (LED), the method comprising:
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a) receiving an AC voltage to obtain a DC voltage signal through a silicon-controlled rectifier (SCR), an electronic transformer, and a rectifier bridge; b) generating an input current and a first output voltage using said DC voltage signal, wherein said input current is generated as a square wave signal during an on time of said SCR, and said input current is maintained as substantially zero during an off time of said SCR; c) generating a dimming signal from said input current; d) generating a constant output current signal using said first output voltage, an LED load current signal, and said dimming signal; and e) wherein, during said on time of said SCR, a peak of said input current is a substantially constant value that satisfies a minimum load current requirement of said electronic transformer, and a valley of said input current is substantially zero. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification