| 摘要 |
<P>PROBLEM TO BE SOLVED: To further prevent burning damage to a printed board by an overcurrent, by continuously turning on an ignition power source even in disconnection and low voltage of a system for driving an IG relay, in a power source device for a vehicle for controlling the ignition power source. <P>SOLUTION: A (+ B) line 12 connected to an on-vehicle power source 10 via a power source line 11 is connected to a relay driving circuit 21. A disconnection detecting circuit 60 for detecting disconnection of the (+ B) line 12 is arranged between the (+ B) line 12 (a (+ B) inside line 25) and an IG line 14 (an IG inside line 26) branched off from the ignition power source 13. A MOSFET 70 with the overcurrent or overheat protective function is arranged between the lines 25 and 26. When the (+ B) line 12 is disconnected, output of a comparator 61 for constituting the disconnection detecting circuit 60 is generated, and the MOSFET 70 is electrically continued. Input voltage is supplied from the IG line 14 to the relay driving circuit 21. <P>COPYRIGHT: (C)2012,JPO&INPIT |
