| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an LED driving circuit with which hardware resources can be suppressed to a lower level than heretofore with respect to an apparatus having an LED lighting at a plurality of luminance levels and an alarm equipped with the same. <P>SOLUTION: The LED driving circuit includes a plurality of series connection objects, each of which consists of serially connected LEDs 1a to 1c, and resistors R3 to R5, and the plurality of series connection objects parallel connected to a DC power source Vcc, and a plurality output ports P1 to P3, each of which is connected to each series connection object, and outputs a control signal for putting the LED into an active state, and a microcomputer 2 for controlling the drive of the plurality of the LEDs 1a to 1c, and the LED driving circuit is equipped with voltage regulation means (Tr1, R1, R2) connected between the DC power source Vcc, and the series connection objects, and a switching element Tr2 connected in parallel to the voltage regulation means (Tr1, R1, R2). The microcomputer 2 further has an output port P4 for outputting the control signal for controlling the operation of the switching element Tr2. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
