Novel power supply soft start circuit

Abstract

The invention provides a novel power supply soft start circuit. The novel power supply soft start circuit comprises a resistor R1, a power supply terminal VCC, a power supply terminal GND, an MOS transistor P0, an MOS transistor P1, a MOS transistor P2, an MOS transistor P3, an MOS transistor P4 and an MOS transistor P5, wherein the drains of the MOS transistor P0, the MOS transistor P1, the MOS transistor P2, the MOS transistor P3, the MOS transistor P4 and the MOS transistor P5 are connected with the power supply terminal VCC through leads; the source of the MOS transistor P0 is connected with one end of the resistor R1 through a lead; the other end of the resistor R1 is grounded through a lead; the gate of the MOS transistor P0 is connected with the gate of the MOS transistor P1 througha lead; the source of the MOS transistor P0 is connected with the gate of the MOS transistor P1 through a lead; and the gate of the MOS transistor P1 is connected with the gate of the MOS transistorP2, the gate of the MOS transistor P3 and the gate of the MOS transistor P4 through leads. Compared with the prior art, the novel power supply soft start circuit has the following beneficial effects that the functions of adjusting charging and discharging currents through a frequency control unit and protecting a power supply circuit are realized.

Description

technical field [0001] The invention is a novel power supply soft start circuit, which belongs to the technical field of switching power supplies. Background technique [0002] Most of the input circuits of switching power supplies use rectification and capacitor filter circuits. At the moment of closing the input circuit, since the initial voltage on the capacitor is zero, a large instantaneous inrush current will be formed. Especially for high-power switching power supplies, the input adopts a larger capacity The filter capacitor, the impact current can reach more than 100A, such a large impact current amplitude at the moment the power is turned on will often cause the input fuse to blow out. The output current of fast charging, but in order to prevent the surge current from charging the capacitor suddenly during startup, resulting in excessive output voltage and causing damage to the circuit, a power supply soft-start circuit will be set in the circuit. The principle is t...

AI Technical Summary

Problems solved by technology

[0002] Most of the input circuits of switching power supplies use rectification and capacitor filter circuits. At the moment of closing the input circuit, since the initial voltage on the capacitor is zero, a large instantaneous inrush current will be formed. Especially for high-power switching power supplies, the input adopts a larger capacity The filter capacitor, the impact current can reach more than 100A, such a large impact current amplitude at the moment the power is turned on will often cause the input fuse to blow out. The output current of fast charging, but in order to prevent the surge current from charging the capacitor suddenly during startup, resulting in excessive output voltage and causing damage to the circuit, a power supply soft-start circuit will be set in the circuit. The principle is that the current source is connected to the capacitor. To prevent excessive voltage, the charging and discharging current in the existing soft-start circuit of the power supply cannot be adjusted, and a large capacitor is required. Because of its large capacitance, it is not easy to put it in the IC

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