| 摘要 |
<P>PROBLEM TO BE SOLVED: To elongate a life of a photocoupler while securing the noise resistance property without increasing current of a light-emitting diode. <P>SOLUTION: An output signal reception circuit has: a first constant current circuit (switching elements MP1 and MP2 and current sources I1 and I2) connected between an input terminal 124 and a high potential side of a DC power supply and discharging current; a second constant current circuit (a current source I3) connected between the input terminal 124 and a low potential side of the DC power supply and absorbing current; and switching elements NM1-NM3 operating the first and second constant current circuits in a complementary manner. The switching elements NM1-NM3 are operated so as to absorb current by means of the second constant current circuit after turning on a photocoupler 21, and operated so as to discharge current by means of the first constant current circuit after turning off the photocoupler 21 and reduce a discharge current value in a current discharge period after a lapse of a constant period from the discharge start. <P>COPYRIGHT: (C)2013,JPO&INPIT |
