Surge suppression circuit

Abstract

The invention discloses a surge suppression circuit which comprises a voltage input end, a voltage output end, a field-effect tube, a transistor, a capacitor, a first resistor, a second resistor and a third resistor, wherein the voltage input end is connected with the source electrode of the field-effect tube and the emitting electrode of the transistor respectively; the voltage input end is also connected with the drain electrode of the field-effect tube through the first resistor; the collector electrode of the field-effect tube is grounded through the third resistor; the base electrode of the transistor is connected with the drain electrode of the field-effect tube through the second resistor; and the drain electrode of the field-effect tube is grounded through the capacitor and also connected with the voltage output end. The surge suppression circuit suppresses surge voltage effectively; after the circuit is in a steady state, the power consumption of the surge suppression circuit is reduced; the surge suppression circuit has the function of load short circuit protection; and when an external power supply generates surge voltage, the surge suppression circuit offers dynamic and real-time protection.

Description

technical field [0001] The invention relates to a power supply protection circuit, in particular to surge suppression of a capacitance filter circuit. Background technique [0002] In the current various electrical appliances, there are a large number of rectification circuits, such as mains, after rectification, capacitor filtering, and then supply power to the conversion circuit of switching power supply; such as traditional power supply, after the mains is stepped down by a transformer, after rectification, capacitor filtering Then supply power to other circuits. When the power switch of this kind of electrical appliances is turned on, due to the existence of the filter capacitor, the voltage at both ends of the filter capacitor is instantly charged from 0V to the rated working voltage, which will generate a large surge voltage and surge current. The inrush current not only shortens the life of the filter capacitor, but also has a greater impact on the diodes, fuses, and ...

AI Technical Summary

Problems solved by technology

The gate and drain are connected as one end, and the source is used as one end, which is equivalent to a Zener diode. Taking an N-channel MOS transistor as an example, the gate and drain are connected as one end, and the source is used as one end, that is, V GS =V DS When the gate and drain terminals are connected to the positive power supply, the source is connected in series with the current limiting resistor and the power supply is negative. At the beginning, the MOS tube is not turned on, and the power supply voltage is raised. This voltage is greater than the turn-on voltage of the MOS tube ( Gate threshold voltage), the MOS tube starts to conduct, and a drain current is generated, due to V GS =V DS , this voltage cannot be further increased, once the voltage increases due to some reason, then V GS Synchronous rise, that is, the gate-to-source voltage rises, the conduction of the MOS transistor is further increased, and the drain current increases sharply, making V DS falling, gate and drain connected together, V GS synchronous fall

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