| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To protect a switching regulator and an LED by rapidly detecting its abnormality when the LED has been opened. <P>SOLUTION: In a process in which switches SW 1-SW 5 are ON/OFF operated by switching signals from a microcomputer 44, and in which lighting of LED 1-LED 5 is controlled by discharging electromagnetic energy accumulated in switching regulators 12-20 to output blocks 22-30, for example, when the LED 1 becomes opened, and an abnormality detecting signal is inputted from an open detection circuit 32 to the external interruption terminal 66 and a signal input terminal 68, the microcomputer 44 determines that the LED 1 has become open from the abnormality detecting signal, and as the external interruption processing to respond to the abnormality detecting signal, only on-duty of the switching signals to the switch SW 1 is made smaller, and the output voltage of the switching regulator 12 is prevented from becoming overvoltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
