| 摘要 |
A load drive apparatus is provided which comprises a switching element 3 connected in series to a DC power source Vcc and an electric load 4, a drive circuit 5 for generating control signals to turn switching element 3 on and off, a thermal detection element 6 for sensing a temperature of switching element 3, an overheat protective circuit 7 for generating an overheat detection signal when thermal detection element 6 senses the temperature of switching element 3 over a predetermined temperature level, and a disconnection detection circuit 11 provided with a current mirror circuit 12 connected between one and the other terminals of thermal detection element 6 for detecting a disconnection in wiring between thermal detection element 6 and overheat protective circuit 7. When overheat protective circuit 7 produces an overheat detection signal or when disconnection detection circuit 11 detects a breaking of wiring between thermal detection element 6 and overheat protective circuit 7, the control signal from drive circuit 5 is prohibited to be given to switching element 3. In case of disconnection in wiring between the thermal detection element 6 and overheat protective circuit 7, the load drive apparatus can prevent thermal damage to the switching element used therein.
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