| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a three-phase power supply phase interruption detection circuit capable of detecting phase interruption, even when only one phase is interrupted. <P>SOLUTION: If either of R-phase or S-phase of the three-phase power supply 100 is interrupted, a period such that the potential at a M-point is at least the bias potential of a transistor 24 is shorter than in the case electric power is properly supplied from the R-phase and the S-phase, so that the period from the time a capacitor 26 is charged once until it is discharged becomes long and the input voltage to a comparator 21 becomes high. Thus, the comparator 21 outputs a "High" signal when the electric power is properly supplied from the R-phase and the S-shape, and a "Low" signal, if at least one of the R-phase or the S-phase is interrupted. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
