| 摘要 |
PURPOSE:To invalidate a power supply state wherein an instantaneous break is caused repeatedly and to protect a load circuit, by starting counting operation after a switch control part is powered on, and generating an output when the counting is carried out up to a specific value and closing a switch part. CONSTITUTION:Electric power AC100V after being lowered at a section 8, rectified on full-wave basis at a section 9, and passed through a diode 14 for separation is smoothed by a capacitor 15, whose output is applied to the counter part 18 consisting of an initializing circuit 16 and a counter 17. The voltage of a capacitor is low, an inverter 22 generates an H-level output, and the counter 17 is cleared immediately after power-on operation. Resistances 10 and 11 and an NOR gate 12 form a clock pulse generation part 13. When the voltage of the capacitor 19 rises, the inverter 22 generates an L-level output and the counter 17 starts counting; when its counted value attains to a specific value, an output is generated at a terminal Qm to stop the counting by closing the NOR gate 12, and a TR25 is turned on to close a switch part 2, supplying a current to a load 4. Consequently, the power source is inhibited from being turned on immediately after an instantaneous break of power supply to relieve a rush current, protecting the load. |
