# US 10,768,241 B2 · Power supply circuit and sound equipment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,768,241 B2 - Document ID: US10768241B2 - Status: Granted - Kind: B2 - Application number: 16/123,342 - Filed: 2018-09-06 - Published: 2019-03-28 - Granted: 2020-09-08 - Earliest claimed: 2017-09-27 - Assignees: Yamaha Corporation - Applicants: Yamaha Corporation - Inventors: Takuya Kataoka; Hitoshi Shima - Web page: https://patentgrep.com/patent/US10768241B2 ## CPC - G01R 31/40: Testing power supplies (testing photovoltaic devices H02S50/10) - G01R 19/16547: {voltage or current in AC supplies (switching for protection H02H; circuits for emergency power supply H02J9/00)} - G01R 31/3004: {Current or voltage test} - G01R 31/3278: {of relays, solenoids or reed switches (measuring contact resistance G01R27/205; high voltage magnetic switches G01R31/3271, G01R31/333; testing electric windings G01R31/72; monitoring of fail safe circuits H01H47/002)} - H02H 1/06: Arrangements for supplying operative power {(power supply arrangements in general G05F, H02M)} - H02H 3/20: responsive to excess voltage - H02H 3/247: having timing means - H02H 9/02: responsive to excess current {(current limitation for voltage regulators G05F1/573; disconnection after limiting H02H3/025)} - H02J 9/06: with automatic change-over {, e.g. UPS systems} - H02M 7/06: using discharge tubes without control electrode or semiconductor devices without control electrode - H03F 1/0211: {with control of the supply voltage or current} - H03F 1/52: Circuit arrangements for protecting such amplifiers {(monitoring arrangements G01R31/28; increasing reliability in communication systems, e.g. using redundancy H04B1/74)} - H03F 3/187: in integrated circuits - H03F 3/217: Class D power amplifiers; Switching amplifiers - H02H 9/001: {limiting speed of change of electric quantities, e.g. soft switching on or off (progressive control of electronic switches for eliminating interferences H03K17/16)} - H03F 2200/03: the amplifier being designed for audio applications - H03G 3/348: {Muting in response to a mechanical action or to power supply variations, e.g. during tuning; Click removal circuits} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - 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) - H03F: AMPLIFIERS - H03G: CONTROL OF AMPLIFICATION ## Abstract A power supply circuit includes an internal power source that receives power supply from an external power source, an abnormality detection circuit that receives power supply from the internal power source to detect abnormalities of the external power source, a protection target circuit that receives the power supply from the external power source, and a protection function unit that restricts electric power supplied to the protection target circuit to a predetermined range, when the abnormality detection circuit detects the abnormalities. ## Claims ### Claim 1 A power supply circuit comprising: an internal power source that receives electric power from an external power source; an abnormality detection circuit that detects abnormalities of the external power source; a protection target circuit that receives the electric power from the external power source; and a protection function unit that restricts electric power supplied to the protection target circuit to a predetermined range, upon the abnormality detection circuit detecting the abnormalities, wherein the external power source includes a first external power source and a second external power source, wherein the internal power source receives electric power from at least one of the first or second external power source, and wherein the abnormality detection circuit detects abnormalities of the second external power source. ### Claim 2 (depends on 1) The power supply circuit according to claim 1, wherein: the internal power source includes a comparator, and the comparator compares a reference voltage and a detection target voltage corresponding to the first external power source to detect abnormalities of the first external power source. ### Claim 3 (depends on 1) The power supply circuit according to claim 1, wherein the abnormalities of the second external power source include a state of high voltage greater than a first predetermined voltage and a state of low voltage less than or equal to a second predetermined voltage. ### Claim 4 (depends on 1) The power supply circuit according to claim 1, wherein the protection function unit relieves restriction of the electric power supplied to the protection target circuit after a predetermined time elapses in a state where the abnormality detection circuit detects no abnormalities. ### Claim 5 (depends on 1) The power supply circuit according to claim 1, wherein the protection target circuit includes a circuit that processes a sound signal. ### Claim 6 (depends on 1) The power supply circuit according to claim 1, wherein the internal power source receives power from the first external power source. ### Claim 7 A sound equipment comprising: a sound processing circuit; and a power supply circuit that supplies electric power to the sound processing circuit, and comprising: an internal power source that receives electric power from an external power source; an abnormality detection circuit that detects abnormalities of the external power source; a protection target circuit that receives the electric power from the external power source; and a protection function unit that restricts electric power supplied to the sound processing circuit to a predetermined range, upon the abnormality detection circuit detecting the abnormalities, wherein the external power source includes a first external power source and a second external power source, wherein the internal power source receives electric power from at least one of the first or second external power source, and wherein the abnormality detection circuit detects abnormalities of the second external power source. ### Claim 8 (depends on 7) The sound equipment according to claim 7, wherein the internal power source receives electric power from the first external power source.