# US 2018/0323716 A1 · Power converter and method of entering skip at a fixed output power in a light load condition independent of magnetizing inductance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0323716 A1 - Document ID: US20180323716A1 - Status: Published application - Kind: A1 - Application number: 16/034,195 - Filed: 2018-07-12 - Published: 2018-11-08 - Earliest claimed: 2016-03-29 - Assignees: Semiconductor Componenents Industries, LLC - Applicants: Semiconductor Components Industries, LLC - Inventors: Ajay Karthik HARI; Bryan Wayne MCCOY - Web page: https://patentgrep.com/patent/US20180323716A1 ## CPC - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - H02M 1/0009: {Devices or circuits for detecting current in a converter} - H02M 1/0035: {using burst mode control} - H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters - 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) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A power converter has a power transistor and inductor coupled in a conduction path with the power transistor. A switching frequency of the power transistor is reduced during a light load condition. A pulse width of a drive signal to the power transistor is controlled to select a current through the inductor and power transistor corresponding to the switching frequency to maintain a fixed output power of the power converter, and further to vary the current through the inductor and power transistor to maintain the fixed output power of the power converter over a range of switching frequencies. A first number of pulses of the drive signal to the power transistor during a first time period sets the fixed output power of the power converter. No pulses of the drive signal are provided during a second time period after the first time period. ## Claims ### Claim 1 A power converter, comprising: a power transistor; and a controller including an input coupled for receiving a signal representative of a current through a conduction path of the power transistor and an output coupled to a control input of the power transistor, wherein the controller establishes a relationship of the current through the power transistor given a primary inductance of a transformer of the power converter that provides fixed output power of the power converter and controls a drive signal to the control input of the power transistor to vary the current through the power transistor in accordance with the relationship to maintain the fixed output power of the power converter. ### Claim 2 (depends on 1) The power converter of claim 1, further including an oscillator comprising an output providing a switching frequency to set the primary inductance. ### Claim 3 (depends on 1) The power converter of claim 1, further including an oscillator comprising a control input coupled for receiving a feedback signal from an output of the power converter and an output providing a switching frequency of the power transistor in response to the feedback signal. ### Claim 4 (depends on 3) The power converter of claim 3, further including a feedback circuit coupled between the output of the power converter and the control input of the oscillator for setting the switching frequency of the power transistor to different values in response to different loads on the power converter. ### Claim 5 (depends on 1) The power converter of claim 1, wherein the transformer includes a primary side inductor coupled in the conduction path of the power transistor, wherein the primary side inductor includes the primary inductance. ### Claim 6 (depends on 1) The power converter of claim 1, wherein the controller maintains the fixed output power of the power converter during a full load condition. ### Claim 7 A power converter, comprising a controller including an input coupled for receiving a signal representative of a current through a primary side inductor of the power converter, wherein the controller establishes a relationship of the current through the primary side inductor given a primary inductance of primary side inductor that provides fixed output power of the power converter and controls a drive signal to vary the current through the primary side inductor in accordance with the relationship to maintain the fixed output power of the power converter. ### Claim 8 (depends on 7) The power converter of claim 7, further including an oscillator comprising an output providing a switching frequency to set the primary inductance. ### Claim 9 (depends on 7) The power converter of claim 7, further including an oscillator comprising a control input coupled for receiving a feedback signal from an output of the power converter and an output providing a switching frequency in response to the feedback signal. ### Claim 10 (depends on 9) The power converter of claim 9, further including a feedback circuit coupled between the output of the power converter and the control input of the oscillator for setting the switching frequency to different values in response to different loads on the power converter. ### Claim 11 (depends on 7) The power converter of claim 7, further including a power transistor coupled in a conduction path of the primary side inductor, wherein the drive signal is applied to a control input of the power transistor. ### Claim 12 (depends on 7) The power converter of claim 7, further including an amplifier including a first input coupled for receiving a reference signal, a second input coupled for receiving the signal representative of the current through the primary side inductor, and an output coupled to the input of the controller. ### Claim 13 (depends on 7) The power converter of claim 7, wherein the controller maintains the fixed output power of the power converter during a full load condition. ### Claim 14 A method of using a power converter, comprising providing a controller including an input coupled for receiving a signal representative of a current through a primary side inductor of the power converter, wherein the controller establishes a relationship of the current through the primary side inductor given a primary inductance of primary side inductor that provides fixed output power of the power converter and controls a drive signal to vary the current through the primary side inductor in accordance with the relationship to maintain the fixed output power of the power converter. ### Claim 15 (depends on 14) The method of claim 14, further including providing an oscillator comprising an output providing a switching frequency to set the primary inductance. ### Claim 16 (depends on 14) The method of claim 14, further including providing an oscillator comprising a control input coupled for receiving a feedback signal from an output of the power converter and an output providing a switching frequency in response to the feedback signal. ### Claim 17 (depends on 16) The method of claim 16, further including providing a feedback circuit coupled between the output of the power converter and the control input of the oscillator for setting the switching frequency to different values in response to different loads on the power converter. ### Claim 18 (depends on 14) The method of claim 14, further including providing a power transistor coupled in a conduction path of the primary side inductor, wherein the drive signal is applied to a control input of the power transistor. ### Claim 19 (depends on 14) The method of claim 14, further including providing an amplifier including a first input coupled for receiving a reference signal, a second input coupled for receiving the signal representative of the current through the primary side inductor, and an output coupled to the input of the controller. ### Claim 20 (depends on 14) The method of claim 14, wherein the controller maintains the fixed output power of the power converter during a full load condition.