AC LED dimmer and dimming method thereby
First Claim
1. An alternating current (AC) light-emitting diode (LED) dimmer, comprising:
- a rectifier to full-wave rectify a voltage from an AC voltage power source to generate a first full-wave rectified voltage;
a voltage converter to generate a second full-wave rectified isolated voltage from the first full-wave rectified voltage, and to generate a pulse enable signal;
a pulse width modulation controller to be supplied with the second full-wave rectified isolated voltage and to generate a pulse width modulation signal with the frequency of the pulse enable signal and with an adjustable duty-cycle ratio to dim an AC LED; and
a switch to be controlled by the pulse width modulation signal to drive the AC LED by selectively providing the AC voltage to the AC LED.
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Abstract
The disclosure relates to an AC LED dimmer and dimming method thereof. The AC LED dimmer includes a rectifier receiving AC voltage from an AC voltage source and full-wave rectifying the AC voltage; a direct current (DC)/DC converter receiving the full-wave rectified voltage from the rectifier, generating a full-wave rectified stepped-up voltage, and generating a pulse enable signal; a pulse width modulation controller receiving the full-wave rectified stepped-up voltage and generating a pulse width modulation signal to dim an AC LED in response to the pulse enable signal; a switch driving the AC LED under control of the pulse width modulation signal, and an electromagnetic interference (EMI) filter to be connected between the AC voltage source and the switch to eliminate electromagnetic interference from the AC voltage source. Accordingly, the dimmer can perform an efficient and linear dimming function and suppress harmonics.
84 Citations
17 Claims
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1. An alternating current (AC) light-emitting diode (LED) dimmer, comprising:
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a rectifier to full-wave rectify a voltage from an AC voltage power source to generate a first full-wave rectified voltage; a voltage converter to generate a second full-wave rectified isolated voltage from the first full-wave rectified voltage, and to generate a pulse enable signal; a pulse width modulation controller to be supplied with the second full-wave rectified isolated voltage and to generate a pulse width modulation signal with the frequency of the pulse enable signal and with an adjustable duty-cycle ratio to dim an AC LED; and a switch to be controlled by the pulse width modulation signal to drive the AC LED by selectively providing the AC voltage to the AC LED. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An alternating current (AC) light-emitting diode (LED) dimming method, comprising:
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first full-wave rectifying a voltage from an AC voltage power source to generate a first full-wave rectified voltage; generating from the first full-wave rectified voltage a second full-wave rectified isolated voltage and a pulse enable signal; generating a pulse width modulation signal with the frequency of the pulse enable signal and with an adjustable duty-cycle ratio to dim an AC LED, wherein the second full-wave rectified isolated voltage is used to generate a pulse width modulation signal; and driving the AC LED by selectively providing the AC voltage to the AC LED according to the pulse width modulation signal. - View Dependent Claims (16, 17)
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Specification