| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a device for protecting a load circuit enabling the miniaturization of an electric wire by using a switch circuit formed by imitating a fuse. <P>SOLUTION: The threshold temperature is set to a temperature which is lower than an allowable temperature of the electric wire used for the load circuit. Then, when a temperature of the electric wire is estimated based on the ambient temperature, the load current, and the load current flow time, and the estimated temperature reaches the threshold temperature, a semiconductor relay S1 is shut off. As a result, when the temperature of the electric wire rises due to overcurrent generation or the like, the circuit can be surely protected at a point of time before the temperature of the electric wire reaches the allowable temperature. Due to this, a conventionally used fuse is not required. <P>COPYRIGHT: (C)2010,JPO&INPIT |
