| 摘要 |
A thermal control circuit (49) for inexpensively protecting the power interface of cordless and dual-mode powered devices (12), such as hand-held power tools and appliances. The powered device includes a motor (11) that is operable in a preselected voltage range. A switch assembly (110) controls the flow of electrical energy to the motor (11). A power module (14, 16) is configured to supply electric power and to mate with the low-voltage DC power tool (12). The power module (14, 16) is adapted to provide a DC voltage in the preselected voltage range suitable for powering the low-voltage DC power tool (12). A case (91) for the power tool (12) has a pre-defined envelope for electrically and mechanically mating with the power module (14, 16). A power interface that includes at least two terminals, electrically couples the power module (14, 16) to the motor (11). The thermal control circuit (49) protects the power interface from damage caused by an overtemperature level. The thermal control circuit (49), in response to detecting an operating temperature that exceeds the overtemperature level, permanently interrupts the flow of electricity from the power module (14, 16) to the motor (11).
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