Direct-current power supply slow startup control circuit

The invention relates to a slow startup control circuit of DC electrical source, comprising a switching transistor VT1 which is connected with a negative RTN input voltage terminal in series, a bleeder circuit which is arranged between a positive VIN input voltage terminal and the negative RTN input voltage terminal, and a capacitor C1 arranged between the negative RTN input voltage terminal and the bleeder node of the bleeder circuit; wherein the control terminal of the switching transistor VT1 is connected with the bleeder node. The circuit employs a MOSFET which serves as the switching transistor to migrate from a pinch-off region to a constant-current region and at last to an ohm area, which is equivalent to that series impedances from big to small are applied to restrain impulse current so as to reach slow startup; meanwhile, a quick charge circuit is added to the control terminal to quicken the shutoff of the MOSFET after charge release; therefore the slow startup control circuit is suitable for occasio