An LED lamp is provided in which the output light intensity of the LEDs in the LED lamp is adjusted based on the input voltage to the LED lamp. The LED lamp comprises one or more LEDs, and an LED driver configured to receive an input voltage and provide regulated current to said one or more LEDs, where the LED driver is configured to adjust the regulated current to said one or more LEDs according to the input voltage to adjust the output light intensity of said one or more LEDs. The LED lamp can be a direct replacement of conventional incandescent lamps in typical wiring configurations found in residential and commercial building lighting applications that use conventional dimmer switches that carry out dimming by changing the input voltage to the LED lamp.
1. A light-emitting diode (LED) lamp, comprising:
one or more LEDs;
a rectifier configured to receive an input voltage and provide rectified input voltage;
a first comparator configured to compare the rectified input voltage with a reference voltage and generate a sensed voltage, said sensed voltage being in a first state while the input voltage is provided and in a second state while the input voltage is not provided due to phase angle switching of the input voltage;
a dimming factor circuit configured to receive the sensed voltage and generate a control signal indicative of the sensed voltage; and
an LED driver configured to receive the input voltage and provide regulated current to said one or more LEDs, the LED driver configured to adjust the regulated current to said one or more LEDs based on the control signal to adjust output light intensity of said one or more LEDs.
2. The LED lamp of claim 1 , wherein the dimming factor circuit generates the control signal to indicate a pulse width of the sensed voltage in the first state.
3. The LED lamp of claim 2 , wherein the dimming factor circuit generates the control signal to have a voltage proportional to the pulse width of the sensed voltage in the first state.
4. The LED lamp of claim 2 , wherein the LED driver comprises a flyback power converter, a power switch of the flyback power converter being switched on and off according to the pulse width of the sensed voltage to provide the regulated current to said one or more LEDs.
5. The LED lamp of claim 4 , wherein the LED driver further comprises a second comparator configured to compare the control signal with a current sense signal indicative of the regulated current through said one or more LEDs to generate a switch control signal, the switch control signal switching on the power switch of the flyback power converter while the control signal has voltage higher than the current sense signal and switching off the power switch while the control signal has voltage lower than the current sense signal.
6. A method of adjusting output light intensity of one or more LEDs of an LED lamp, the method comprising:
rectifying an input voltage to the LED lamp;
comparing the rectified input voltage with a reference voltage to generate a sensed voltage, said sensed voltage being in a first state while the input voltage is provided and in a second state while the input voltage is not provided due to phase angle switching of the input voltage;
generating a control signal indicative of the sensed voltage; and
adjusting regulated current to said one or more LEDs based on the control signal to adjust the output light intensity of said one or more LEDs.
7. The method of claim 6 , wherein the control signal is generated to indicate a pulse width of the sensed voltage in the first state.
8. The method of claim 7 , wherein the control signal is generated to have a voltage proportional to the pulse width of the sensed voltage in the first state.
9. The method of claim 7 , wherein said one or more LEDs are driven by a flyback power converter, a power switch of the flyback power converter being switched on and off according to the pulse width of the sensed voltage to provide the regulated current to said one or more LEDs.
10. The method of claim 9 , further comprising comparing the control signal with a current sense signal indicative of the regulated current through said one or more LEDs to generate a switch control signal, the switch control signal switching on the power switch of the flyback power converter while the control signal has voltage higher than the current sense signal and switching off the power switch while the control signal has voltage lower than the current sense signal.
11. A lamp device, comprising:
one or more light-emitting means for emitting light according to current flowing through said light-emitting means; and
rectifier means for receiving an input voltage and providing rectified input voltage;
comparator means for comparing the rectified input voltage with a reference voltage and generating a sensed voltage, said sensed voltage being in a first state while the input voltage is provided and in a second state while the input voltage is not provided due to phase angle switching of the input voltage;
dimming control means for receiving the sensed voltage and generating a control signal indicative of the sensed voltage; and
driver means for receiving the input voltage and providing regulated current to said one or more light-emitting means, the driver means configured to adjust the regulated current to said one or more light-emitting means based upon the control signal to adjust output light intensity of said one or more light-emitting means.