Power supply fault protection circuit with primary side shutdown and restart
First Claim
1. A fault protection system for a power supply having a primary side and secondary side separated by a galvanic barrier, the system comprising:
- a fault detection circuit configured to declare a fault mode in response to fault detection;
an isolated control circuit configured to deliver a shutdown signal from the secondary side to the primary side without violating the galvanic barrier, in response to an indication of fault from the fault detection circuit;
an auxiliary power circuit having an output node from which current to the fault detection circuit is provided during the fault mode; and
a switch circuit configured to connect the isolated control circuit to the auxiliary power circuit during the fault mode, so that an auxiliary current can flow through the isolated control circuit to the output node of the auxiliary power circuit.
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Accused Products
Abstract
Fault protection circuitry and methodologies for isolated power supply topologies are provided. The circuitry is configured to shut down the primary side of the supply in case of a system fault, while keeping the secondary side circuit running, thus offering flexibility for restarting upon clearing of the fault. A lighting driver thus configured with safety isolation and a secondary side microcontroller or other control circuitry, is configured so that the circuit can shut down the primary side in response to system fault detection, while keeping the secondary microcontroller running from an energy storage circuit (e.g., bulk capacitor in parallel with load). The driver operation can resume with a controlled timing if the fault is cleared. The number of restarts may be limited, and/or a timer may be used to space restarts. The driver may be used with loads other than lighting-based loads, as will be appreciated.
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Citations
20 Claims
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1. A fault protection system for a power supply having a primary side and secondary side separated by a galvanic barrier, the system comprising:
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a fault detection circuit configured to declare a fault mode in response to fault detection; an isolated control circuit configured to deliver a shutdown signal from the secondary side to the primary side without violating the galvanic barrier, in response to an indication of fault from the fault detection circuit; an auxiliary power circuit having an output node from which current to the fault detection circuit is provided during the fault mode; and a switch circuit configured to connect the isolated control circuit to the auxiliary power circuit during the fault mode, so that an auxiliary current can flow through the isolated control circuit to the output node of the auxiliary power circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A lighting driver, comprising:
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a primary side and a secondary side separated by a galvanic barrier, wherein the secondary side includes a storage circuit configured to be electrically connected in parallel with a light source configured to be driven by the lighting driver; a fault detection circuit configured to declare a fault mode in response to fault detection, and to clear the fault mode in response to at least one of expiration of a shutdown timer, a successful fault mitigation, and a restart counter being less than a permanent shutdown threshold value; an isolated control circuit configured to deliver a shutdown signal from the secondary side to the primary side without violating the galvanic barrier, in response to an indication of fault mode from the fault detection circuit; an auxiliary power circuit having an output node from which current to the fault detection circuit is provided during the fault mode; and a switch circuit configured to connect the isolated control circuit to the auxiliary power circuit, so that an auxiliary current can flow from the storage circuit through the isolated control circuit to the output node of the auxiliary power circuit, the switch circuit comprising a first transistor that turns on in response to the shutdown signal from the fault detection circuit and a second transistor that turns on in response to the first transistor turning of, the second transistor allowing the auxiliary current to flow from the isolated control circuit to the output node. - View Dependent Claims (14, 15, 16)
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17. A method of powering a load using a power supply having a primary side and secondary side separated by a galvanic barrier, the method comprising:
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declaring a fault mode, via a fault detection circuit, in response to fault detection; delivering, via an isolated control circuit, a shutdown signal from the secondary side to the primary side without violating the galvanic barrier, in response to a declared fault mode from the fault detection circuit; providing an auxiliary power circuit having an output node from which current to the fault detection circuit is provided during the declared fault mode; connecting, via a switch circuit, the isolated control circuit to the auxiliary power circuit, so that an auxiliary current can flow through the isolated control circuit to the output node of the auxiliary power circuit, the switch circuit comprising a first transistor that turns on in response to the shutdown signal and a second transistor that turns on in response to the first transistor turning off, the second transistor allowing the auxiliary current to flow from the isolated control circuit to the output node. - View Dependent Claims (18, 19, 20)
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Specification