Power supply control device having a control unit for estimating a smoking temperature of a switch element

A power supply control device comprising:

• a switch element provided at a midpoint in an electrical wire that connects a power supply and a load;
• a current detection unit that detects a current value of a current flowing in the electrical wire;
• a temperature estimation unit that estimates a wire temperature of the electrical wire based on the current value detected by the current detection unit and a heat dissipation time constant of the electrical wire;
• and
• a control unit that performs control to turn on or off the switch element based on the wire temperature estimated by the temperature estimation unit;
• wherein the control unit calculates a threshold temperature that is lower than both a temperature indicated by a smoking characteristic of the switch element and a temperature indicated by a smoking characteristic of the electrical wire, wherein the threshold temperature is calculated by changing the heat dissipation time constant of the electrical wire used to estimate the wire temperature to a smaller value;
• and
• the control unit performs control to turn off the switch element if the wire temperature estimated by the temperature estimation unit is greater than or equal to the threshold temperature.