| 摘要 |
An object of the present invention is to inexpensively and surely protect a FET against an overcurrent, via which electric power is supplied from a high-voltage DC power source to a load. Electric power is supplied from a high-voltage DC power source 63 to a load 66 via a FET 60. A drain-source voltage detecting circuit 2 detects a drain-source voltage V DS of the FET 60. A first overcurrent protection signal generating circuit 7 outputs a first overcurrent protection signal based on the drain-source voltage V DS of the FET 60. A second overcurrent protection signal generating circuit 8 outputs a second overcurrent protection signal based on a gradient increase (increasing rate) of the drain-source voltage V DS of the FET 60. A control circuit 16 turns off the FET 60 to protect the FET 60 against an overcurrent when the first overcurrent protection signal is output from the first overcurrent protection signal generating circuit 7 or the second overcurrent protection signal is output from the second overcurrent protection signal generating circuit 8. |
