| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an LED driving circuit that avoids breakage of a switch element even when causing the element breakage, disconnection and so on in an LED etc. <P>SOLUTION: The LED driving circuit includes a reactor L1 which stores electric power energy for supplying a current to the LED 10, the switch element Q1, a current detecting resistance R1 which detects the current flowing to the switch element Q1, a constant-current circuit 2 which generates a first control signal for controlling the current flowing to the switch element Q1 to a constant current, a disconnection detecting circuit 4a which generates a second control signal for maintaining the switch element Q1 in an off state when it is determined, based upon the current detected by the current detecting resistance R1 and the first control signal, that a current larger than a predetermined value is flowing to the switch element Q1 a predetermined time after timing of switching of the switch element Q1 from an on state to the off state, and a switch element driving circuit 3 which maintains the switch element Q1 in the off state with priority to the first control signal during disconnection based upon the second control signal. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
