# US 8,569,972 B2 · Dimmer output emulation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,972 B2 - Document ID: US8569972B2 - Status: Granted - Kind: B2 - Application number: 12/858,164 - Filed: 2010-08-17 - Published: 2012-02-23 - Granted: 2013-10-29 - Earliest claimed: 2010-08-17 - Assignees: Cirrus Logic, Inc. - Applicants: John L. Melanson - Inventors: John L. Melanson - Web page: https://patentgrep.com/patent/US8569972B2 ## CPC - H05B 45/14: using electrical feedback from LEDs or from LED modules - H05B 45/10: Controlling the intensity of the light - H05B 45/3725: Switched mode power supply [SMPS] - H05B 47/10: Controlling the light source - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract A lighting system includes a dimmer output voltage emulator to cause a power converter interface circuit to generate an emulated dimmer output voltage. In at least one embodiment, the emulated dimmer output voltage corresponds to an actual dimmer output voltage but is unaffected by non-idealities in the dimmer output voltage, such as premature shut-down of a triac-based dimmer. By generating an emulated dimmer output voltage, the energy delivered to a load, such as a lamp, corresponds to a dimming level setting. ## Claims ### Claim 1 An apparatus comprising: a dimmer output voltage emulator configured to cause a power converter interface circuit to draw current from a capacitor in the power converter interface during a period of time when a dimmer coupled to the power converter interface circuit is non-conducting to generate an emulated dimmer output voltage, wherein the emulated dimmer output voltage emulates part of a cycle of a non-zero alternating current dimmer output voltage of the dimmer after a triac of the dimmer prematurely stops conducting that would occur if the triac continued conducting during the part of the cycle. ### Claim 2 (depends on 1) The apparatus of claim 1 wherein the emulated dimmer output voltage is generally decreasing over time during the emulated part of the dimmer output voltage cycle. ### Claim 3 (depends on 1) The apparatus of claim 1 wherein the emulated dimmer output voltage comprises multiple linear segments each having a unique slope. ### Claim 4 (depends on 1) The apparatus of claim 1 wherein the emulated dimmer output voltage comprises a concave parabolic waveform. ### Claim 5 (depends on 1) The apparatus of claim 1 wherein the dimmer output voltage emulator is further configured to provide current that interacts with components of the power interface circuit to provide the emulated dimmer output voltage. ### Claim 6 (depends on 1) The apparatus of claim 1 wherein the dimmer output voltage emulator comprises a pull-down circuit to pull-down current of the power converter interface circuit and generally decrease the emulated dimmer output voltage during a first period of time and a glue circuit to maintain the emulated dimmer output voltage below a threshold value during a second period of time. ### Claim 7 (depends on 6) The apparatus of claim 6 wherein the glue circuit provides a steady state current draw from the power converter interface circuit to maintain the emulated dimmer output voltage below the threshold value during the second period of time. ### Claim 8 (depends on 6) The apparatus of claim 6 wherein the first period of time begins when a triac of a triac-based dimmer circuit ceases conducting during a cycle of an AC supply voltage, the second period of time begins when the supply voltage is below the threshold voltage, the first period ends when the second period begins, and the second period ends when the supply voltage begins to increase. ### Claim 9 A method comprising: causing a power converter interface circuit to draw current from a capacitor in the power converter interface during a period of time when a dimmer coupled to the power converter interface circuit is non-conducting to generate an emulated dimmer output voltage, wherein the emulated dimmer output voltage emulates part of a cycle of a non-zero alternating current dimmer output voltage of the dimmer after a triac of the dimmer prematurely stops conducting that would occur if the triac continued conducting during the part of the cycle. ### Claim 10 (depends on 9) The method of claim 9 wherein causing the power converter interface circuit to generate an emulated dimmer output voltage comprises generally decreasing the emulated dimmer output voltage over time during the emulated part of the dimmer output voltage cycle. ### Claim 11 (depends on 9) The method of claim 9 wherein causing the power converter interface circuit to generate an emulated dimmer output voltage causing the power converter interface circuit to generate the emulated dimmer output voltage to include multiple linear segments each having a unique slope. ### Claim 12 (depends on 9) The method of claim 9 wherein causing the power converter interface circuit to generate an emulated dimmer output voltage causing the power converter interface circuit to generate the emulated dimmer output voltage comprises generating the emulated dimmer output voltage to include a convex parabolic waveform. ### Claim 13 (depends on 9) The method of claim 9 further comprising: providing current that interacts with components of the power interface circuit to provide the emulated dimmer output voltage. ### Claim 14 (depends on 9) The method of claim 9 further comprising: pulling-down current of the power converter interface circuit to generally decrease the emulated dimmer output voltage during a first period of time; and maintaining the emulated dimmer output voltage below a threshold value during a second period of time. ### Claim 15 (depends on 14) The method of claim 14 further comprising: drawing a steady state current from the power converter interface circuit to maintain the emulated dimmer output voltage below the threshold value during the second period of time. ### Claim 16 (depends on 14) The method of claim 14 wherein the first period of time begins when a triac of a triac-based dimmer circuit ceases conducting during a cycle of an AC supply voltage, the second period of time begins when the supply voltage is below the threshold voltage, the first period ends when the second period begins, and the second period ends when the supply voltage begins to increase. ### Claim 17 (depends on 9) The method of claim 9 further comprising: generating an emulated dimmer output voltage in a power converter interface circuit, wherein the emulated dimmer output voltage emulates part of a cycle of an alternating current dimmer output voltage of the dimmer. ### Claim 18 An apparatus comprising: a dimmer; a power converter interface circuit coupled to the dimmer; a dimmer output voltage emulator, coupled to the power converter interface circuit, wherein (i) the dimmer output voltage emulator is configured to cause the power converter interface circuit to draw current from a capacitor in the power converter interface during a period of time when the dimmer coupled to the power converter interface circuit is non-conducting to generate an emulated dimmer output voltage and (ii) the emulated dimmer output voltage emulates part of a cycle of an alternating current dimmer output voltage of the dimmer; a power converter coupled to the dimmer output voltage emulator; and a controller coupled to the dimmer output voltage emulator and the power converter, wherein the controller is configured to control the power converter in accordance with the emulated dimmer output voltage. ### Claim 19 (depends on 18) The apparatus of claim 18 wherein: the dimmer comprises a triac-based dimmer; and the power converter is a switching power converter. ### Claim 20 An apparatus comprising: means for causing a power converter interface circuit to draw current from a capacitor in the power converter interface during a period of time when a dimmer coupled to the power converter interface circuit is non-conducting to generate an emulated dimmer output voltage, wherein the emulated dimmer output voltage emulates part of a cycle of a non-zero alternating current dimmer output voltage of the dimmer after a triac of the dimmer prematurely stops conducting that would occur if the triac continued conducting during the part of the cycle. ### Claim 21 (depends on 18) The apparatus of claim 18 wherein the emulated dimmer output voltage emulates part of a cycle of a non-zero portion of the alternating current dimmer output voltage of the dimmer after a triac of the dimmer prematurely stops conducting that would occur if the triac continued conducting during the part of the cycle.