# US 2010/0165683 A1 · Switching power supply circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0165683 A1 - Document ID: US20100165683A1 - Status: Published application - Kind: A1 - Application number: 12/654,619 - Filed: 2009-12-24 - Published: 2010-07-01 - Earliest claimed: 2008-12-25 - Assignees: Fuji Electric Systems Co., Ltd. - Inventors: Takato Sugawara - Web page: https://patentgrep.com/patent/US20100165683A1 ## CPC - H02M 1/4225: {using a non-isolated boost converter} - 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 switching power supply circuit that obtains a predetermined DC voltage output from an input AC power supply includes a full-wave rectifier and a boost circuit connected to the rectifier. The boost circuit generates a DC output having a predetermined voltage value from the rectifier output. A power factor improving circuit controls an ON-period of an output transistor of the boost circuit, based on feedback of the DC voltage output, and a dynamic over-voltage-protection circuit controls the ON-period of the output transistor as it performs a switching operation. The switching power supply circuit facilitates an over-voltage-protection function that prevents inductor buzzing with an integrated circuit having a small number of pins. ## Claims ### Claim 1 A switching power supply circuit configured to produce a DC voltage output from an input AC power supply, the switching power supply circuit comprising: a full-wave rectifier configured to full-wave rectify the input AC power supply; a boost circuit configured to generate the DC voltage output with a predetermined voltage value from an output terminal voltage of the rectifier, the boost circuit including a boost inductance element having a first end connected to an output terminal of the rectifier, a switching device connected between a second end of the inductance element and a reference potential, a rectifying device, and a capacitor connected to the second end of the inductance element via the rectifying device; and a power factor controller configured to control an ON-period of the switching device based on an error signal obtained by amplifying a difference between feedback of the DC voltage output and a reference voltage; the power factor controller configured to compare the DC voltage output feedback with a first protection voltage as the reference voltage, for shortening the ON-period of the switching device by an amount of time corresponding to a difference between the DC voltage output feedback and the first protection voltage. ### Claim 2 (depends on 1) The switching power supply circuit according to claim 1, wherein the power factor controller includes: a zero-cross detection circuit configured to detect a zero-cross time of an inductor current of the inductance element, for generating a signal that turns the switching device ON; an oscillator circuit configured to output an oscillation signal that increases monotonically at a time at which the switching device is turned ON; a comparator circuit configured to generate a signal that turns the switching device OFF if a value of the oscillation signal reaches a value of the error signal; and a dynamic over-voltage-protection circuit configured to monitor the DC voltage output feedback and cause the oscillator circuit to increase a gradient at which the oscillation signal increases monotonically, the increase corresponding to the difference between the first protection voltage and the DC voltage output feedback. ### Claim 3 (depends on 2) The switching power supply circuit according to claim 2, wherein the power factor controller further includes a static over-voltage-protection circuit configured to use a second protection voltage higher than the first protection voltage as the reference voltage. ### Claim 4 (depends on 2) The switching power supply circuit according to claim 2, wherein: the oscillator circuit includes an integration circuit configured to charge a capacitor with a constant current and to use a charging voltage of the capacitor for the oscillation signal; and the dynamic over-voltage-protection circuit is configured to generate an additional charging current having a magnitude corresponding to the difference between the DC voltage output feedback and the first protection voltage, for charging the capacitor. ### Claim 5 (depends on 4) The switching power supply circuit according to claim 4, wherein the power factor controller further includes a static over-voltage-protection circuit configured to use a second protection voltage higher than the first protection voltage for the reference voltage. ### Claim 6 A power supply circuit to generate a DC voltage output, comprising: a power factor controller configured to control an ON-period of a switching device of the power supply circuit, based on a difference between the DC voltage output and a reference voltage; wherein, to control the ON-period, the power factor controller is configured to compare a feedback of the DC voltage output with a first protection voltage as the reference voltage, and to shorten the ON-period of the switching device by an amount of time corresponding to a difference between the DC voltage output feedback and the first protection voltage. ### Claim 7 (depends on 6) The power supply circuit according to claim 6, wherein the power factor controller further includes a static over-voltage-protection circuit configured to use a second protection voltage higher than the first protection voltage as the reference voltage. ### Claim 8 A method comprising: comparing a DC voltage output of a power supply circuit with a reference voltage; and controlling an ON-period of a switching device of the power supply circuit, based on a difference between the DC voltage output and a reference voltage. ### Claim 9 (depends on 8) The method of claim 8, the controlling comprising shortening the ON-period of the switching device by an amount of time corresponding to the difference.