# US 8,542,468 B2 · Fault condition protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,468 B2 - Document ID: US8542468B2 - Status: Granted - Kind: B2 - Application number: 13/451,383 - Filed: 2012-04-19 - Published: 2012-08-16 - Granted: 2013-09-24 - Earliest claimed: 1998-11-16 - Assignees: Power Integrations, Inc. - Applicants: Balu Balakrishnan; Alex B. Djenguerian; Leif Lund - Inventors: Balu Balakrishnan; Alex B. Djenguerian; Leif Lund - Web page: https://patentgrep.com/patent/US8542468B2 ## CPC - H02M 1/32: Means for protecting converters other than automatic disconnection - F16D 31/02: using pumps with pistons or plungers working in cylinders - H02H 7/1213: {for DC-DC converters} - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - B29C 45/82: Hydraulic {or pneumatic} circuits - B29C 2045/824: {Accumulators} - H02M 1/36: Means for starting or stopping converters - 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) - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES - 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) - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) ## Abstract A switched mode power supply includes a transformer and an integrated circuit regulator. The integrated circuit regulator is coupled to the transformer and includes switching regulator logic, a counter, and a switching transistor. The regulator logic generates a switching signal in response to the feedback signal. The counter receives the feedback signal, where the feedback signal periodically cycles between a first state and a second state when the switched mode power supply operates normally. An output of the counter indicates an auto-restart mode of the regulator in response to the feedback signal remaining in the first state for a predetermined count due to a fault condition. The switching transistor is coupled to be turned on and off in response to the switching signal when the output of the counter does not indicate the auto-restart mode and is disabled when the output of the counter indicates the auto-restart mode. ## Claims ### Claim 1 A switched mode power supply, comprising: a transformer having a primary winding and a secondary winding magnetically coupled to the primary winding, the secondary winding configured to provide an output; and an integrated circuit regulator coupled to the transformer, the integrated circuit regulator including: switching regulator logic coupled to receive a feedback signal representative of the output, the switching regulator logic to generate a switching signal in response to the feedback signal to control power delivered to the output; a counter coupled to receive the feedback signal, wherein the feedback signal periodically cycles between a first state and a second state when the switched mode power supply operates normally and wherein an output of the counter indicates an auto-restart mode of the regulator in response to the feedback signal remaining in the first state for a predetermined count due to a fault condition; and a switching transistor coupled to the primary winding of the transformer and coupled to be turned on and off in response to the switching signal when the output of the counter does not indicate the auto-restart mode, the switching transistor further coupled to be disabled when the output of the counter indicates the auto-restart mode. ### Claim 2 (depends on 1) The switched mode power supply of claim 1, wherein the output of the counter is an output bit corresponding to the predetermined count. ### Claim 3 (depends on 1) The switched mode power supply of claim 1, wherein the counter is coupled to be reset each time the feedback signal cycles to the second state. ### Claim 4 (depends on 1) The switched mode power supply of claim 1, wherein the feedback signal transitions between the first state and the second state independently from the switching signal. ### Claim 5 (depends on 1) The switched mode power supply of claim 1, wherein the integrated circuit regulator further comprises an oscillator coupled to provide a clock signal to the switching regulator logic, wherein the switching regulator logic generates the switching signal in response to the feedback signal and the clock signal. ### Claim 6 (depends on 5) The switched mode power supply of claim 5, wherein the counter is coupled to receive the clock signal and to increment a count of the counter in response to the clock signal. ### Claim 7 (depends on 5) The switched mode power supply of claim 5, wherein the oscillator outputs the clock signal having a first frequency in response to the output of the counter not indicating the auto-restart mode and wherein the oscillator outputs the clock signal having a second frequency in response to the output of the counter indicating the auto-restart mode. ### Claim 8 (depends on 7) The switched mode power supply of claim 7, wherein the second frequency is less than the first frequency. ### Claim 9 (depends on 8) The switched mode power supply of claim 8, wherein the second frequency is one-fourth the first frequency. ### Claim 10 (depends on 7) The switched mode power supply of claim 7, wherein the integrated circuit regulator further comprises: a first current source included in the oscillator, wherein the oscillator outputs the clock signal at the first frequency when the first current source is turned on; and a second current source coupled to the oscillator, wherein the oscillator outputs the clock signal at the second frequency when the second current source is turned on. ### Claim 11 (depends on 10) The switched mode power supply of claim 10, wherein the first current source is turned on and the second current source is turned off in response to the output of the counter not indicating the auto-restart mode. ### Claim 12 (depends on 10) The switched mode power supply of claim 10, wherein the first current source is turned off and the second current source is turned on in response to the output of the counter indicating the auto-restart mode. ### Claim 13 (depends on 10) The switched mode power supply of claim 10, wherein the second current source is coupled to supply a current that is less than a current supplied by the first current source. ### Claim 14 (depends on 1) The switched mode power supply of claim 1, wherein the integrated circuit regulator further comprises a logic gate having a first input coupled to receive the switching signal, a second input coupled to receive the output of the counter, and an output that is coupled to the switching transistor, wherein the output of the logic gate enables the switching transistor to turn on and off in response to the switching signal when the output of the counter does not indicate the auto-restart mode and wherein the output of the logic gate disables the switching transistor in response to the output of the counter indicating the auto-restart mode.