| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a power supply control device capable of stabilizing to the rated amperage in a short time after switching-on without using any fuse for circuit protection by supply controlling the load current on the fuse fusion characteristic curve. SOLUTION: A power supply control device is equipped with a comparator circuit to judge whether an over-current is flowing upon determining the difference between the drain-source voltage of an over-heat self-shutoff type semiconductor switch QA and the drain-source voltage of an over-heat self-shutoff type semiconductor switch QB and comparing the obtained difference with the specified over-current reference value, a driver circuit 2 to turn on and off the switch QA with a control signal according to the sensing signal, and a microcomputer 8 which stores the current supply value for the time from the switch turn-on to attainment of the rated current, conducts time measurement at starting, and executes on-off control of the switch QA, whereby on-off of the switch QA is repeated in accordance with the result from comparison, and judgement of shortcircuited condition is passed when a specified frequency of occurrence of the switch QA being turned off is generated, and it is put off.</p> |
