# US 9,882,498 B2 · Switching power supply device, switching power supply control method, and electronic apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,882,498 B2 - Document ID: US9882498B2 - Status: Granted - Kind: B2 - Application number: 14/284,843 - Filed: 2014-05-22 - Published: 2014-12-04 - Granted: 2018-01-30 - Earliest claimed: 2013-05-29 - Assignees: Sony Corporation - Applicants: Sony Corporation - Inventors: Hiroyuki Watanabe - Web page: https://patentgrep.com/patent/US9882498B2 ## CPC - H02M 3/33546: {with automatic control of the output voltage or current (H02M3/33561 takes precedence)} - H02M 1/4241: {using a resonant converter} - H02M 7/4815: {Resonant converters (H02M7/4811 and H02M7/4826 take precedence)} - H02M 7/523: with LC-resonance circuit in the main circuit - 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 device includes a switching element to which a DC input is supplied, a frequency control circuit which controls a switching frequency of the switching element, a frequency detection circuit which detects the switching frequency of the switching element, and a duty ratio control circuit which controls a switching duty ratio based on the frequency detected by the frequency detection circuit. The duty ratio control circuit controls the switching duty ratio such that the switching frequency becomes an approximately maximum frequency. ## Claims ### Claim 1 A switching power supply device comprising: a switching element to which a direct current (DC) input is supplied; a frequency control circuit which controls a switching frequency of the switching element; a frequency detection circuit which detects the switching frequency of the switching element; and a duty ratio control circuit which controls a switching duty ratio based on the switching frequency detected by the frequency detection circuit, wherein the duty ratio control circuit controls the switching duty ratio such that the switching frequency becomes an approximately maximum frequency, and wherein the duty ratio control circuit operates using the switching duty ratio in an area where a slope of a change of the switching frequency with respect to a change of the switching duty ratio becomes positive. ### Claim 2 (depends on 1) The switching power supply device according to claim 1, further comprising: a transformer; a resonance circuit; and a rectification circuit, wherein the switching element is configured by a first switching element and a second switching element which are connected in series and alternately turned on by the switching frequency, wherein output currents of the first and second switching elements are supplied to the transformer, wherein the resonance circuit is connected to a primary side of the transformer, and the rectification circuit is connected to a secondary side of the transformer, and wherein an output voltage is stabilized by a frequency of a switching signal which is controlled by a feedback signal. ### Claim 3 (depends on 2) The switching power supply device according to claim 2, wherein a time of changing the switching duty ratio is set so as to be longer than a response time which is determined from a band of the feedback signal. ### Claim 4 (depends on 1) The switching power supply device according to claim 1, wherein the duty ratio control circuit performs a duty ratio control operation. ### Claim 5 A switching power supply control method of a switching power supply device including a switching element to which a direct current (DC) input is supplied, a frequency control circuit which controls a switching frequency of the switching element, a frequency detection circuit which detects the switching frequency of the switching element, and a duty ratio control circuit which controls a switching duty ratio based on the switching frequency detected by the frequency detection circuit, the method comprising: detecting the switching frequency of the switching element; and controlling the switching duty ratio based on the switching frequency detected by the frequency detection circuit such that the switching frequency becomes an approximately maximum frequency, wherein the duty ratio control circuit operates using the switching duty ratio in an area where a slope of a change of the switching frequency with respect to a change of the switching duty ratio becomes positive. ### Claim 6 An electronic apparatus comprising: a switching power supply device, wherein the switching power supply device includes a switching element to which a direct current (DC) input is supplied; a frequency control circuit which controls a switching frequency of the switching element; a frequency detection circuit which detects the switching frequency of the switching element; and a duty ratio control circuit which controls a switching duty ratio based on the switching frequency detected by the frequency detection circuit, wherein the duty ratio control circuit controls the switching duty ratio such that the switching frequency becomes an approximately maximum frequency, and wherein the duty ratio control circuit operates using the switching duty ratio in an area where a slope of a change of the switching frequency with respect to a change of the switching duty ratio becomes positive. ### Claim 7 (depends on 5) The switching power supply control method according to claim 5, further including: alternately turning on first and second switching elements of the switching element according to the switching frequency; providing output currents of the first and second switching elements to a transformer; and stabilizing an output voltage in accordance with a frequency of a switching signal controlled by a feedback signal. ### Claim 8 (depends on 5) The switching power supply control method according to claim 5, wherein a time of changing the switching duty ratio is set so as to be longer than a response time which is determined from a band of a feedback signal. ### Claim 9 (depends on 5) The switching power supply control method according to claim 5, wherein the duty ratio control circuit performs a duty ratio control operation. ### Claim 10 (depends on 6) The electronic apparatus according to claim 6, further comprising: a transformer; a resonance circuit; and a rectification circuit, wherein the switching element is configured by a first switching element and a second switching element which are connected in series and alternately turned on by the switching frequency, wherein output currents of the first and second switching elements are supplied to the transformer, wherein the resonance circuit is connected to a primary side of the transformer, and the rectification circuit is connected to a secondary side of the transformer, and wherein an output voltage is stabilized by a frequency of a switching signal which is controlled by a feedback signal. ### Claim 11 (depends on 6) The electronic apparatus according to claim 6, wherein a time of changing the switching duty ratio is set so as to be longer than a response time which is determined from a band of a feedback signal. ### Claim 12 (depends on 6) The electronic apparatus according to claim 6, wherein the duty ratio control circuit performs a duty ratio control operation. ### Claim 13 (depends on 1) The switching power supply device according to claim 1, wherein the switching frequency relates to a fixed value of an ON period of the switching element.