CIRCUIT FOR PREVENTING INRUSH CURRENT

摘要

PURPOSE: A circuit for preventing an inrush current is provided to prevent the IC(Integrated Circuit) breakdown and mis-operation by dualizing the flow of the inrush current. CONSTITUTION: A poly switching unit(PTC21) is connected to a first power input line out of first and second power input lines when an inrush current is flowed into and rises a resistance value to firstly restrain the flow of a current. An electrode of a current limiting switching unit is connected to the poly switching unit(PTC21). The current limiting switching unit secondly restrains the current passing through the poly switching unit(PTC21) to switch to an input terminal of a to-be-protected circuit. An anode of a first Zener diode(ZD21) is connected to an output side of the poly switching unit(PTC21) and a cathode thereof is connected to a gate of the current limiting switching unit. The first Zener diode(ZD21) limits the current flowed into the gate. An anode of a second Zener diode(ZD22) is connected to the other electrode of the current limiting switching unit and a cathode thereof is connected to a second input line. The second Zener diode(ZD22) prevents the inrush current. A side of a first resistance unit(R21) is connected to the poly switching unit(PTC21) and the other side thereof is connected to the input terminal of the to-be-protected circuit. The first resistance unit(R21) is parallel with the current limiting switching unit.