PREVENTING DEVICE OF RUSH CURRENT AND PROTECTING DEVICE OF ELECTRONIC CIRCUIT

PURPOSE: To realize a preventing device of a rush current which dispenses with a switch for switching-over the connection of a current limiting resistor and can suppress the rush current sufficiently even when it is used for an electronic device consuming a large current. CONSTITUTION: Regarding a preventing device of a rush current which prevents the rush current flowing into an electronic device when a power supply is connected through connectors, a semiconductor switching element 36 is connected by insertion to a power supply line connecting a plus-side power supply connecting pin 37 of a first connector 32a, a capacitor 34 and an electronic circuit 35 of the electronic device 31, and the on-resistance of this semiconductor switching element 36 is controlled so that it may be changed gradually from infinity, i.e., a practically insulated state, to practically 0Ω until a prescribed time elapses after each connector is connected. When the connectors are connected according to this constitution, the semiconductor switching element 36 operates as a current limiting resistor and thereby can prevent occurrence of the rush current and also it can suppress the rush current sufficiently even for the electronic device consuming a large current.