Patent ID: 7409277

Claim:
A driving circuit for a crew protection device connected to a DC power source and mounted in a vehicle comprising: a squib for operating the protection device when a preset amount of electric current is supplied thereto from said DC power source; a first transistor connected between one end of said squib and one end of said DC power source; a second transistor connected between the other end of said squib and the other end of said DC power source; and transistor control means for controlling said first transistor when a command signal is given thereto; wherein said transistor control means controls said first transistor to pass a first preset amount of electric current if output voltage of said DC power source is higher than a first threshold voltage and to pass an amount of electric current so that the voltage across the first transistor can be set to be equal to or lower than a second threshold voltage if output voltage of said DC power source becomes higher than the threshold voltage.