# US 2014/0152187 A1 · Circuits and methods for driving a light source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152187 A1 - Document ID: US20140152187A1 - Status: Published application - Kind: A1 - Application number: 13/705,546 - Filed: 2012-12-05 - Published: 2014-06-05 - Earliest claimed: 2012-12-05 - Assignees: O2 Micro, Inc. - Applicants: O2 Micro Inc. - Inventors: Yung Lin LIN; Tiesheng YAN; Ching-Chuan KUO - Web page: https://patentgrep.com/patent/US20140152187A1 ## CPC - H05B 45/10: Controlling the intensity of the light - H05B 45/14: using electrical feedback from LEDs or from LED modules - H05B 45/3725: Switched mode power supply [SMPS] - Y02B 20/30: Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED] - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A circuit includes a bridge circuit, a converter, and a controller. The bridge circuit receives power from first and second power lines of a switch and generates a rectified voltage. The switch is capable of operating in a first state in which the switch conducts power to the first power line but not the second power line, a second state in which the switch conducts power to the second power line but not the first power line, and a third state in which the switch conducts power to both the first and second power lines. The converter converts the rectified voltage to an output voltage to drive a light source, and controls a current through the light source according to a driving signal. The controller monitors the operation state of the switch and generates the driving signal based on the operation state to control brightness/dimming of the light source. ## Claims ### Claim 1 A circuit for driving a light source, said circuit comprising: a bridge circuit coupled to a switch through a first power line and a second power line, and configured to receive power from said first and second power lines and generate a rectified voltage, wherein said switch operates in a plurality of operation states comprising a first state, a second state, and a third state, wherein in said first state said switch conducts power to said first power line but not said second power line, wherein in said second state said switch conducts power to said second power line but not said first power line, and wherein in said third state said switch conducts power to both said first and second power lines; a converter coupled to said bridge circuit and configured to convert said rectified voltage to an output voltage to drive said light source, and control a current through said light source according to a driving signal; and a controller coupled to said converter and configured to monitor said operation state of said switch and generate said driving signal based on said operation state to control the light level of said light source. ### Claim 2 (depends on 1) The circuit as claimed in claim 1, wherein said controller adjust an average current flowing through said light source to a first level, a second level, and a third level, respectively, when said three-way switch operates in said first state, said second state, and said third state, respectively. ### Claim 3 (depends on 1) The circuit as claimed in claim 1, wherein said bridge circuit rectifies a power voltage on said first power line to generate said rectified voltage when said three-way switch operates in said first state, and rectifies a power voltage on said second power line to generate said rectified voltage when said three-way switch operates in said second state. ### Claim 4 (depends on 1) The circuit as claimed in claim 1, wherein said bridge circuit combines power voltages on said first and second power lines to a combined voltage, and rectifies said combined voltage to generate said rectified voltage when said switch operates in said third state. ### Claim 5 (depends on 1) The circuit as claimed in claim 1, wherein said bridge circuit comprises: a plurality of diode units coupled in parallel, each of said diode units comprising a plurality of diodes in series, wherein said diode units comprise a first diode unit, a second diode unit, and a third diode unit, wherein said first diode unit is further coupled to said first power line, and wherein further said second diode unit is coupled to said second power line. ### Claim 6 (depends on 5) The circuit as claimed in claim 5, wherein said first diode unit and said third diode unit constitute a bridge rectifier to generate said rectified voltage when said switch operates in said first state, and wherein said first diode unit, said second diode unit, and said third diode unit constitute a bridge rectifier to generate said rectified voltage when said switch operates in said third state. ### Claim 7 (depends on 1) The circuit as claimed in claim 1, wherein said controller further comprises: a signal generator configured to receive a first detection signal indicating a power voltage on said first power line, receive a second detection signal indicating a power voltage on said second power line, and generate a reference signal indicating a target level for an average current through said light source according to said first and second detection signals; and a driver coupled to said signal generator and configured to generate said driving signal according to said reference signal to adjust said average current to said target level. ### Claim 8 (depends on 7) The circuit as claimed in claim 7, wherein said signal generator sets said reference signal to a first value, a second value, and a third value, respectively, when said first and second detection signals indicate that said switch operates in said first state, said second state, and said third state, respectively. ### Claim 9 (depends on 1) The circuit as claimed in claim 1, wherein said controller comprises: a compensator configured to receive a sense signal indicating a current through said light source, receive a first detection signal indicating the power voltage on said first power line, receive a second detection signal indicating the power voltage on said second power line, provide an offset signal according to said first and second detection signals, and compensate said sense signal based on said offset signal to generate a compensation signal; and a driver coupled to said compensator and configured to generate said driving signal according to said compensation signal to adjust said average current to a target level. ### Claim 10 (depends on 9) The circuit as claimed in claim 9, wherein said compensator sets said offset signal to a first value, a second value, and a third value, respectively, when said first and second detection signals indicate that said switch operates in said first state, said second state, and said third state, respectively. ### Claim 11 A controller for controlling power to a light emitting diode (LED) light source, said controller comprising: a pair of detection pins coupled to a three-way switch through a first power line and a second power line, and configured to detect an operation state of said three-way switch comprising a first state, a second state, and a third state, wherein in said first state said three-way switch conducts power to said first power line but not said second power line, wherein in said second state said three-way switch conducts power to said second power line but not said first power line, wherein in said third state said three-way switch conducts power to both said first power line and said second power line, wherein a power converter receives power from said three-way switch and provides an output voltage to drive said LED light source; and an output pin configured to generate a driving signal according to said operation state to control said power converter, such that an average current through said LED light source is adjusted to a first level, a second level, and a third level when said three-way switch operates in said first, second, and third operation states, respectively. ### Claim 12 (depends on 11) The controller as claimed in claim 11, wherein a bridge circuit coupled between said power converter and said three-way switch provides a rectified voltage by rectifying a first power voltage on said first power line when said three-way switch operates in said first state, and by rectifying a second power voltage on said second power line when said three-way switch operates in said second state. ### Claim 13 (depends on 12) The controller as claimed in claim 12, wherein said bridge circuit combines said first power voltage and said second power voltage into a combined voltage, and rectifies said combined voltage to provide said rectified voltage when said three-way switch operates in said third state. ### Claim 14 (depends on 11) The controller as claimed in claim 11, further comprising: a signal generator configured to generate a reference signal indicating a target level for an average current through said LED light source according to said operation state; and a driver coupled to said signal generator and configured to generate said driving signal according to said reference signal to adjust said average current to said target level, wherein said reference signal has a first value, a second value, and a third value, respectively, when said three-way switch operates in said first state, said second state, and said third state, respectively. ### Claim 15 (depends on 11) The controller as claimed in claim 11, further comprising: a sense pin configured to receive a sense signal indicating a current through said LED light source; a compensator coupled to said sense pin and configured to provide an offset signal according to said operation state, and compensate said sense signal based on said offset signal to generate a compensation signal; and a driver coupled to said compensator and configured to generate said driving signal according to said compensation signal to adjust said average current to a target level, wherein said offset signal is set to a first value, a second value, and a third value, respectively, when said three-way switch operates in said first state, said second state, and said third state, respectively. ### Claim 16 A method for driving a light emitting diode (LED) light source, said method comprising: receiving power from a three-way switch having a first power line and a second power line, wherein said three-way switch operates in a plurality of operation states comprising a first state, a second state, and a third state, wherein in said first state said switch conducts power to said first power line but not said second power line, wherein in said second state said switch conducts power to said second power line but not said first power line, and wherein in said third state said switch conducts power to both said first and second power lines; providing an output voltage to drive said LED light source; monitoring in which state said three-way switch operates; and generating a driving signal based on said operation state of said three-way switch to control a current through said LED light source. ### Claim 17 (depends on 16) The method as claimed in claim 16, further comprising: adjusting an average current flowing through said LED light source to a first level, a second level, and a third level, respectively, when said three-way switch operates in said first state, said second state, and said third state, respectively. ### Claim 18 (depends on 16) The method as claimed in claim 16, further comprising: rectifying a power voltage on said first power line to generate a rectified voltage when said three-way switch operates in said first state; rectifying a power voltage on said second power line to generate said rectified voltage when said three-way switch operates in said second state; combining said power voltages on said first and second power lines to a combined voltage when said three-way switch operates in said third state; rectifying said combined voltage to generate said rectified voltage when said three-way switch operates in said third state; and converting said rectified voltage to said output voltage to drive said LED light source. ### Claim 19 (depends on 16) The method as claimed in claim 16, further comprising: receiving a first detection signal indicating a power voltage on said first power line; receiving a second detection signal indicating a power voltage on said second power line; generating a reference signal indicating a target level for an average current through said LED light source according to said first and second detection signals; and generating said driving signal according to said reference signal to adjust said average current to said target level. ### Claim 20 (depends on 19) The method as claimed in claim 19, further comprising: setting said reference signal to a first value, a second value, and a third value, respectively, when said first and second detection signals indicate that said three-way switch operates in said first state, said second state, and said third state, respectively. ### Claim 21 (depends on 16) The method as claimed in claim 16, further comprising: receiving a sense signal indicating a current through said LED light source; receiving a first detection signal indicating the power voltage on said first power line; receiving a second detection signal indicating the power voltage on said second power line; providing an offset signal according to said first and second detection signals; compensating said sense signal based on said offset signal to generate a compensation signal; and generating said driving signal according to said compensation signal to adjust said average current to a target level. ### Claim 22 (depends on 21) The method as claimed in claim 21, further comprising: setting said offset signal to a first value, a second value, and a third value, respectively, when said first and second detection signals indicate that said three-way switch operates in said first state, said second state, and said third state, respectively.