# US 11,445,582 B2 · Zero current controlled dimming circuit and a method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,445,582 B2 - Document ID: US11445582B2 - Status: Granted - Kind: B2 - Application number: 17/182,790 - Filed: 2021-02-23 - Published: 2021-09-23 - Granted: 2022-09-13 - Earliest claimed: 2020-03-17 - Assignees: Chengdu Monolithic Power Systems Co., Ltd. - Applicants: Chengdu Monolithic Power Systems Co., Ltd. - Inventors: Hui Li; Siran Wang - Web page: https://patentgrep.com/patent/US11445582B2 ## CPC - H02M 3/1588: {comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence)} - H05B 45/14: using electrical feedback from LEDs or from LED modules - H02M 1/0009: {Devices or circuits for detecting current in a converter} - H02M 1/0025: {Arrangements for modifying reference values, feedback values or error values in the control loop of a converter} - H02M 1/083: {for the ignition at the zero crossing of the voltage or the current} - H05B 45/345: Current stabilisation; Maintaining constant current - H05B 45/3725: Switched mode power supply [SMPS] - Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - 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 control circuit of a zero current controlled dimming circuit having a high side power switch, a low side power switch and an inductor, having: an error circuit, providing a compensation signal based on a reference signal and a current sense signal indicative of an output current; a compensation circuit, providing a compensation off time signal based on the compensation signal and a peak value sample and hold signal indicative of a peak value of an inductor current; and a control signal generating circuit, providing a low side switch control signal to control the low side power switch based on the compensation off time signal, wherein after the inductor current decreases to zero, the low side power switch maintains on for a compensation off time period determined by the compensation off time signal. ## Claims ### Claim 1 A control circuit of a zero current controlled dimming circuit having a high side power switch, a low side power switch and an inductor, and providing an output current to a load, the control circuit comprising: an error circuit, configured to provide a compensation signal based on a reference signal and a current sense signal indicative of the output current; a compensation circuit, configured to provide a compensation off time signal based on the compensation signal and a peak value sample and hold signal indicative of a peak value of an inductor current flowing through the inductor; and a control signal generating circuit, configured to provide a low side switch control signal to control the low side power switch based on the compensation off time signal, wherein after the inductor current decreases to zero, the low side power switch maintains on for a compensation off time period determined by the compensation off time signal. ### Claim 2 (depends on 1) The control circuit of claim 1, wherein the error circuit comprises an amplifier. ### Claim 3 (depends on 1) The control circuit of claim 1, wherein the compensation circuit comprises: a difference circuit, having a first input terminal configured to receive the peak value sample and hold signal, a second input terminal configured to receive the compensation signal, and an output terminal configured to provide a time period control signal based on a difference of the peak value sample and hold signal, and the compensation signal; and a compensation signal generating circuit, having a first input terminal configured to receive the time period control signal, a second input terminal configured to receive a slope reference signal, and an output terminal configured to provide the compensation off time signal. ### Claim 4 (depends on 3) The control circuit of claim 3, wherein the difference circuit comprises a subtractor. ### Claim 5 (depends on 3) The control circuit of claim 3, wherein the compensation signal generating circuit comprises a comparator. ### Claim 6 (depends on 1) The control circuit of claim 1, further comprising: a zero-cross detecting circuit, configured to provide a zero-crossing signal based on a drain-source voltage across the low side power switch, wherein the zero-crossing signal flips when the drain-source voltage across the low side power switch crosses zero; and a slope reference signal generating circuit, configured to provide a slope reference signal based on the zero-crossing signal. ### Claim 7 (depends on 6) The control circuit of claim 6, wherein the control signal generating circuit comprises: a logic circuit, configured to provide the low side switch control signal based on the compensation off time signal and the zero-crossing signal. ### Claim 8 (depends on 1) The control circuit of claim 1, wherein the control signal generating circuit comprises: a reference signal generating circuit, configured to provide a reference off time signal; and a logic circuit, configured to provide the low side switch control signal based on the compensation off time signal and the reference off time signal. ### Claim 9 A zero current controlled dimming circuit, comprising: a high side power switch; a low side power switch, coupled in series with the high side power switch; an inductor, having a first terminal coupled to a connection node of the high side power switch and the low side power switch, and a second terminal coupled to an input voltage or an output voltage; an error circuit, configured to provide a compensation signal based on a reference signal and a current sense signal indicative of an output current of the zero current controlled dimming circuit; a compensation circuit, configured to provide a compensation off time signal based on the compensation signal and a peak value sample and hold signal indicative of a peak value of an inductor current flowing through the inductor; and a control signal generating circuit, configured to provide a low side switch control signal to control the low side power switch based on the compensation off time signal, wherein after the inductor current decreases to zero, the low side power switch maintains on for a compensation off time period determined by the compensation off time signal. ### Claim 10 (depends on 9) The zero current controlled dimming circuit of claim 9, wherein the compensation circuit comprises: a difference circuit, having a first input terminal configured to receive the peak value sample and hold signal, a second input terminal configured to receive the compensation signal, and an output terminal configured to provide a time period control signal based on a difference of the peak value sample and hold signal, and the compensation signal; and a compensation signal generating circuit, having a first input terminal configured to receive the time period control signal, a second input terminal configured to receive a slope reference signal, and an output terminal configured to provide the compensation off time signal. ### Claim 11 (depends on 10) The zero current controlled dimming circuit of claim 10, wherein the compensation signal generating circuit comprises a comparator. ### Claim 12 (depends on 10) The zero current controlled dimming circuit of claim 10, wherein the difference circuit comprises a subtractor, and the time period control signal has a magnitude being a value of the peak value sample and hold signal minus the compensation signal. ### Claim 13 (depends on 9) The zero current controlled dimming circuit of claim 9, further comprising: a zero-cross detecting circuit, configured to provide a zero-crossing signal based on a drain-source voltage across the low side power switch, wherein the zero-crossing signal flips when the drain-source voltage across the low side power switch crosses zero; and a slope reference signal generating circuit, configured to provide a slope reference signal based on the zero-crossing signal. ### Claim 14 (depends on 13) The zero current controlled dimming circuit of claim 13, wherein the control signal generating circuit comprises: a logic circuit, configured to provide the low side switch control signal based on the compensation off time signal and the zero-crossing signal. ### Claim 15 (depends on 9) The zero current controlled dimming circuit of claim 9, wherein the control signal generating circuit comprises: a reference signal generating circuit, configured to provide a reference off time signal; and a logic circuit, configured to provide the low side switch control signal based on the compensation off time signal and the reference off time signal. ### Claim 16 A control method of a zero current controlled dimming circuit having a high side power switch, a low side power switch and an inductor, the control method comprising: generating a compensation signal based on a current sense signal indicating an output current of the zero current controlled dimming circuit, and a reference signal; generating a time period control signal based on the compensation signal and a peak value sample and hold signal indicating a peak value of an inductor current flowing through the inductor of the zero current controlled dimming circuit; generating a compensation off time signal based on the time period control signal and a slope reference signal; and controlling the low side power switch being on for a compensation off time period after the inductor current flowing through the inductor decreases to zero. ### Claim 17 (depends on 16) The control method of claim 16, wherein the slope reference signal increases from zero when a drain-source voltage across the low side power switch crosses zero from negative to positive. ### Claim 18 (depends on 16) The control method of claim 16, further comprising: generating a zero-crossing signal based on a drain-source voltage across the low side power switch, wherein the zero-crossing signal flips when the drain-source voltage crosses zero; and generating a low side switch control signal based on the zero-crossing signal and the compensation off time signal, wherein the low side switch control signal determines an on time period of the low side power switch in a switching period. ### Claim 19 (depends on 16) The control method of claim 16, further comprising: generating a reference off time signal; and generating a low side switch control signal based on the reference off time signal and the compensation off time signal; wherein wherein the low side switch control signal determines an on time period of the low side power switch in a switching period.