Thermal protection device to withstand high voltage
AssigneeLittelfuse, Inc.
InventorsToshikazu Yamaoka, Yohei Mizukami, Jianhua Chen, Werner Johler
Life of this patent
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Abstract
A thermal protection device, comprising: a first PTC device, arranged in a PTC circuit, and having a first input side, coupled to an input path of the PTC circuit, and having a first output side, coupled to an output path of the PTC circuit; a second PTC device, arranged in the PTC circuit, and having a second input side, coupled to the input path of the PTC circuit, and having a second output side, coupled to the output path of the PTC circuit; and a thermal link having a third input side, coupled to the first output side of the first PTC device and the second output side of the second PTC device, via the output path of the PTC circuit.
Claims13
A thermal protection circuit, comprising:
- a first PTC device, arranged in a PTC circuit, and having a first input side, coupled to an input path of the PTC circuit, and having a first output side, coupled to an output path of the PTC circuit;
- a second PTC device, arranged in the PTC circuit, and having a second input side, coupled to the input path of the PTC circuit, and having a second output side, coupled to the output path of the PTC circuit;
- and
- a thermal link having a third input side, coupled to the first output side of the first PTC device and the second output side of the second PTC device, via the output path of the PTC circuit;
- wherein the first PTC device comprises a first trip temperature PTCT1, wherein the second PTC device comprises a second trip temperature PTCT2, wherein the thermal link comprises a melting temperature TM, wherein PTCT1, <TM.<PTCT2.
A method of providing thermal protection, comprising:
- conducting current through a protection circuit, the protection circuit comprising a first PTC device and a second PTC device, arranged in electrically parallel fashion to one another within a PTC circuit, and further comprising a thermal link, arranged in electrical series to the PTC circuit;
- and
- responsive to an abnormal condition, changing the first PTC device from a normal state to a tripped state, wherein the second PTC device transitions from a normal conduction state to a tripped state after the PTC device is changed from the normal state to the tripped state, and wherein the second PTC device causes the thermal link to melt;
- wherein the first PTC device comprises a first trip temperature, and wherein the second PTC device comprises a second trip temperature, greater than the first trip temperature.
Dependencies are inferred from the claim text.