| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an LED switching controller such that all LED arrays do not turn off completely and a constant-current circuit does not enter an abnormal heat generation state either even if a plurality of LED arrays include a LED array to which no current flows owing to breaking of a wire etc. <P>SOLUTION: In a control circuit 4a, a second selection detecting circuit 9 and a switching circuit 10 are newly provided. When a protection circuit 7 detects an overvoltage state from a raised output voltage, the switching circuit 10 having received a protection signal from the protection circuit 7 switches a signal to be supplied to an error amplifier circuit 6 from the output signal of a first selection detecting circuit 5 to the output signal of the second selection detecting circuit 9. Consequently, the output voltage of a DC-DC converter circuit 1 is controlled according to the voltage across the constant-current circuit connected to a LED array where the smallest forward voltage drop detected by the second selection detecting circuit 9 appears. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
