| 摘要 |
PURPOSE:To prevent the damage of a semiconductor element controlled by a triangular wave comparing circuit output by inhibiting the output for a short period in the vicinity of the positive and negative peaks of the triangular wave. CONSTITUTION:This comparing circuit has a triangular wave signal generator 37, a comparator 33 of an input signal Vin with a triangular wave signal, a comparator 34 of the voltage of one terminal of a low voltage diodes ZD1-4 connected between the diagonal points of a triangular wave signal amplitude determining diode bridge circuit 36, and a comparator 35 having an output terminal connected commonly to the output terminals of the comarator 33, 34 for comparing the voltage of the other terminal of the constant voltage diodes ZD1-4 with the voltage of the adding point 31 of a rectangular wave. The output signals of the comparators 33-35 are inhibited during the predetermined period of time before and after the triangular wave signal Vin passes the positive and negative peaks. |
