# US 2014/0197739 A1 · DC-DC Converter Protection Circuit and Protection Method Thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197739 A1 - Document ID: US20140197739A1 - Status: Published application - Kind: A1 - Application number: 14/155,441 - Filed: 2014-01-15 - Published: 2014-07-17 - Earliest claimed: 2013-01-17 - Assignees: uPI Semiconductor Corp. - Applicants: Upi Semiconductor Corp. - Inventors: Wen-Fu Lu - Web page: https://patentgrep.com/patent/US20140197739A1 ## CPC - H02H 7/1213: {for DC-DC converters} - H02H 9/041: {using a short-circuiting device} - H05B 45/38: using boost topology - H05B 45/50: responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits - H05B 47/24: Circuit arrangements for protecting against overvoltage - H05B 47/25: Circuit arrangements for protecting against overcurrent - Y02B 20/30: Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED] - 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) - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A protection circuit of a DC-DC converter is disclosed. An input terminal of the DC-DC converter receives an input voltage and an output terminal of the DC-DC converter provides an output voltage. The DC-DC converter includes an output stage between the input terminal and the output terminal The protection circuit includes a current sensor, a comparator, a determining circuit, and a protection control circuit. The current sensor provides a sensing signal. The comparator compares a default over-voltage with the sensing signal to provide an over-current control signal. The determining circuit provides a determining control signal. The protection control circuit determines whether to enable a short protection according to the over-current control signal and the determining control signal. ## Claims ### Claim 1 A protection circuit of a DC-DC converter, the DC-DC converter comprising an input terminal, an output terminal, and an output stage, the input terminal receiving an input voltage and the output terminal providing an output voltage, the output stage being disposed between the input terminal and the output terminal, the protection circuit comprising: a current sensor, coupled to at least one circuit unit of the output stage and providing a sensing signal; a first comparator, coupled to the current sensor and comparing a default over-voltage with the sensing signal to provide an over-current control signal; a determining circuit, providing a determining control signal; and a protection control circuit, coupled to the determining circuit and the first comparator and determining whether to enable a short protection according to the over-current control signal and the determining control signal. ### Claim 2 (depends on 1) The protection circuit of claim 1, wherein the determining circuit comprises a first feedback circuit and a second comparator, the first feedback circuit provides a feedback control signal, the second comparator is coupled to the first feedback circuit and provides the determining control signal according to the feedback control signal and a first default voltage. ### Claim 3 (depends on 1) The protection circuit of claim 1, wherein the determining circuit comprises a first feedback circuit and a second comparator, the second comparator is coupled to the first feedback circuit, the first feedback circuit comprises an error amplifier for receiving a first feedback voltage and a reference voltage, when the over-current control signal indicates an over-current event, if the first feedback voltage is larger than the reference voltage, the protection control circuit turns off a transistor of the output stage according to the over-current control signal and the determining control signal. ### Claim 4 (depends on 1) The protection circuit of claim 1, wherein the determining circuit comprises a first feedback circuit and a second comparator, the second comparator is coupled to the first feedback circuit, the first feedback circuit comprises an error amplifier for receiving a first feedback voltage and a reference voltage and providing a feedback control signal according to the first feedback voltage and the reference voltage, when the over-current control signal indicates an over-current event, if the first feedback voltage is smaller than the reference voltage and the feedback control signal is larger than a first default voltage, the protection control circuit enables the short protection according to the determining control signal provided by the second comparator. ### Claim 5 (depends on 1) The protection circuit of claim 1, wherein the determining circuit comprises a time control circuit coupled to the first comparator, when the over-current control signal indicates an over-current event, the time control circuit counts a default time, when the default time is over, if the over-current control signal still indicates the over-current event, the time control circuit controls the protection control circuit to enable the short protection. ### Claim 6 (depends on 1) The protection circuit of claim 1, wherein when the over-current control signal indicates an over-current event, the determining circuit counts a default time, when the default time is over, if the over-current control signal still indicates the over-current event, the determining circuit provides the determining control signal. ### Claim 7 (depends on 1) The protection circuit of claim 1, further comprising a second feedback circuit and a third comparator, the second feedback circuit provides a second feedback voltage, the third comparator compares the second feedback voltage with a second default voltage to provide an over-voltage control signal, and the protection control circuit enables an open protection according to the over-voltage control signal. ### Claim 8 (depends on 1) The protection circuit of claim 1, wherein the output terminal of the DC-DC converter is coupled to at least one LED string, the determining circuit comprises a first feedback circuit, and the first feedback circuit is coupled to the at least one LED string to form a circuit for protecting a LED driving circuit. ### Claim 9 (depends on 1) The protection circuit of claim 1, wherein a protection switch is coupled between the input terminal and the output stage and coupled to the protection control circuit, when the protection control circuit enables the short protection, and the protection control circuit turns off the protection switch. ### Claim 10 A protection method of a DC-DC converter, the DC-DC converter comprising an input terminal, an output terminal, and an output stage, the input terminal receiving an input voltage and the output terminal providing an output voltage, the output stage being disposed between the input terminal and the output terminal, the protection method comprising steps of: (a) providing a sensing signal; (b) comparing a default over-voltage with the sensing signal to provide an over-current control signal; (c) providing a determining control signal; and (d) determining whether to enable a short protection according to the over-current control signal and the determining control signal. ### Claim 11 (depends on 10) The protection method of claim 10, wherein the step (c) provides the determining control signal according to a feedback control signal and a first default voltage. ### Claim 12 (depends on 10) The protection method of claim 10, further comprising steps of: when the over-current control signal indicates an over-current event, determining whether the first feedback voltage is larger than the reference voltage; and if the first feedback voltage is larger than the reference voltage, turning off a transistor of the output stage according to the over-current control signal and the determining control signal. ### Claim 13 (depends on 10) The protection method of claim 10, further comprising steps of: providing a feedback control signal according to the first feedback voltage and the reference voltage; when the over-current control signal indicates an over-current event, determining whether the first feedback voltage is smaller than the reference voltage and whether the feedback control signal is larger than a first default voltage respectively; and if the first feedback voltage is smaller than the reference voltage and the feedback control signal is larger than a first default voltage, enabling the short protection according to the determining control signal provided by the step (c). ### Claim 14 (depends on 10) The protection method of claim 10, further comprising steps of: when the over-current control signal indicates an over-current event, counting a default time; and when the default time is over, if the over-current control signal still indicates the over-current event, enabling the short protection. ### Claim 15 (depends on 10) The protection method of claim 10, further comprising steps of: when the over-current control signal indicates an over-current event, counting a default time; and when the default time is over, if the over-current control signal still indicates the over-current event, enabling the short protection according to the determining control signal provided by the step (c). ### Claim 16 (depends on 10) The protection method of claim 10, further comprising steps of: providing a second feedback voltage; comparing the second feedback voltage with a second default voltage to provide an over-voltage control signal; and enabling an open protection according to the over-voltage control signal.