LED Lamp

• US 20100013409A1
• Filed: 07/16/2008
• Published: 01/21/2010
• Est. Priority Date: 07/16/2008
• Status: Active Grant

• Current Assignee: Dialog Semiconductor Incorporated (Renesas Electronics Corporation)
• Original Assignee: iWatt, Inc. (Renesas Electronics Corporation)
• Inventors: Chen, Gordon, Quek, Eng Hwee, Muegge, Mark R.
• Granted Patent: US 7,936,132 B2
• Time in Patent Office: Days
• US Class Current: 315/294
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/31 Phase-control circuits
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

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.

Claims

1. A light-emitting diode (LED) lamp, comprising:

one or more LEDs; and

an LED driver configured to receive an 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 according to the input voltage to adjust output light intensity of said one or more LEDs.

2. The LED lamp of claim 1, further comprising a dimming factor circuit configured to sense the input voltage and generate a control signal indicative of the sensed input voltage, the LED driver being configured to adjust the regulated current to said one or more LEDs based upon the control signal.

3. The LED lamp of claim 2, further comprising:

a rectifier configured to receive the input voltage and provide rectified input voltage; and

a first comparator configured to compare the rectified input voltage with a reference voltage and generate said sensed input voltage, said sensed input 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.

4. The LED lamp of claim 3, wherein the dimming factor circuit generates the control signal to indicate a pulse width of the sensed input voltage in the first state.

5. The LED lamp of claim 4, wherein the dimming factor circuit generates the control signal to have a voltage proportional to the pulse width of the sensed input voltage in the first state.

6. The LED lamp of claim 4, 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 input voltage to provide the regulated current to said one or more LEDs.

7. The LED lamp of claim 6, 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.

8. The LED lamp of claim 1, further comprising a voltage averaging circuit configured to receive the input voltage and generate a control signal indicative of an average DC value of the input voltage, the LED driver being configured to adjust the regulated current to said one or more LEDs based upon the control signal.

9. The LED lamp of claim 1, further comprising:

a voltage divider coupled to receive the input voltage and configured to generate a scaled input voltage;

a filter coupled to the voltage divider and configured to filter AC components of the scaled input voltage to generate a control signal indicative of the an average DC value of the scaled input voltage, the LED driver being configured to adjust the regulated current to said one or more LEDs based upon the control signal.

10. The LED lamp of claim 9, wherein the voltage divider is a resistive voltage divider including a first resistor and a second resistor, and the filter includes a capacitor connected in parallel to the second resistor.

11. A method of adjusting output light intensity of one or more LEDs of an LED lamp, the method comprising:

sensing an input voltage to the LED lamp; and

adjusting regulated current to said one or more LEDs according to the sensed input voltage to adjust the output light intensity of said one or more LEDs.

12. The method of claim 11, further comprising generating a control signal indicative of the sensed input voltage, the regulated current being adjusted based upon the control signal.

13. The method of claim 12, further comprising:

rectifying the input voltage; and

comparing the rectified input voltage with a reference voltage to generate said sensed input voltage, said sensed input 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.

14. The method of claim 13, wherein the control signal is generated to indicate a pulse width of the sensed input voltage in the first state.

15. The method of claim 14, wherein the control signal is generated to have a voltage proportional to the pulse width of the sensed input voltage in the first state.

16. The method of claim 14, 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 input voltage to provide the regulated current to said one or more LEDs.

17. The method of claim 16, 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.

18. The method of claim 11, further comprising generating a control signal indicative of an average DC value of the input voltage, the regulated current to said one or more LEDs being adjusted based upon the control signal.

19. The method of claim 11, further comprising:

generating a scaled one of the input voltage;

filtering AC components of the scaled input voltage to generate a control signal indicative of an average DC value of the scaled input voltage, the regulated current to said one or more LEDs being adjusted based upon the control signal.

20. A lamp device, comprising:

one or more light-emitting means for emitting light according to current flowing through said light-emitting means; and

driver means for receiving an 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 according to the input voltage to adjust output light intensity of said one or more light-emitting means.

21. The lamp device of claim 20, further comprising sensing means for sensing the input voltage and generating a control signal indicative of the sensed input voltage, the driver means being configured to adjust the regulated current to said one or more light-emitting means based upon the control signal.

22. The lamp device of claim 20, further comprising voltage averaging means for receiving the input voltage and generating a control signal indicative of an average DC value of the input voltage, the driver means being configured to adjust the regulated current to said one or more light-emitting means based upon the control signal.