CN105186474A

CN105186474A - Protection circuit

Info

Publication number: CN105186474A
Application number: CN201510432732.2A
Authority: CN
Inventors: 仝兴孚
Original assignee: PUYANG LIYUAN AUTO ELECTRIC Co Ltd
Current assignee: PUYANG LIYUAN AUTO ELECTRIC Co Ltd
Priority date: 2015-07-22
Filing date: 2015-07-22
Publication date: 2015-12-23

Abstract

The invention relates to a protection circuit. The protection circuit comprises field effect transistors; the drain of the field effect transistor Q1 and the drain of the field effect transistor Q2 are respectively connected with the input ends of a transformer T; a resistor R3 is connected between the gate and source of the field effect transistor Q1; a resistor R4 is connected between the gate and source of the field effect transistor Q2; an input signal is connected with the gate of the field effect transistor Q1 through a resistor R1; the other input signal is connected with the gate of the field effect transistor Q2 through a resistor R2; the source of the field effect transistor Q1 is connected with the source of the field effect transistor Q2 and is connected with the source or drain of the field effect transistor Q3; the drain or source of the field effect transistor Q3 is grounded; and the gate of the field effect transistor Q3 is connected with a power source end through a resistor R5. The protection circuit of the invention has the advantages of simple structure, ingenious design and stable and reliable operation.

Description

A kind of protective circuit

technical field:

The present invention relates to a kind of circuit, be specifically related to a kind of protective circuit.

background technology:

In many electronic circuits, easy powered overload impact, can cause the situation damaging other overvoltage or overcurrent; Also have power supply to connect instead, or the overcurrent that causes due to electronic circuit itself make power supply or load circuit cause damage; Also have in the circuit of some other use field effect transistor; under normal circumstances, the source electrode of field effect transistor is directly grounded, some protective circuits are inoperative to field effect transistor in such cases; and in same circuit, design these protective circuits some complexity rather simultaneously, be unfavorable for practical application.

summary of the invention:

The present invention provides a kind of multifunctional protection circuit for problems of the prior art exactly.

Technical scheme provided by the invention is:

A kind of protective circuit, comprise field effect transistor, the drain electrode of field effect transistor Q1 is connected with the input of transformer T respectively with the drain electrode of field effect transistor Q2, contact resistance R3 between the grid of field effect transistor Q1 and source electrode, contact resistance R4 between the grid of field effect transistor Q2 and source electrode, input signal connects the grid of field effect transistor Q1 by resistance R1, another input signal connects the grid of field effect transistor Q2 by resistance R2, the source electrode of field effect transistor Q1 is connected with the source electrode of field effect transistor Q2 and is connected with the source electrode of field effect transistor Q3 or drain, the drain electrode of field effect transistor Q3 or source ground, the grid of field effect transistor Q3 connects power end by resistance R5.

Concrete, the grid of described field effect transistor Q3 also connects power end by diode D, and the positive pole of diode D is connected with the grid of field effect transistor Q3.

Concrete, the grid of described field effect transistor Q3 also connects thermistor RT, the other end ground connection of thermistor RT.

Concrete, the described input signal by resistance R1 is pulse signal, is pulse signal by the input signal of resistance R2, and by the pulse input signal of resistance R1 be alternately input by the pulse input signal of resistance R2.

Structure of the present invention is simple, design concept is ingenious, circuit operates steadily reliably, in this circuit running, the source electrode of field effect transistor Q1 is connected with the source electrode of field effect transistor Q2 and is connected with the source electrode of field effect transistor Q3 or drain, and the drain electrode of field effect transistor Q3 or source ground, the advantage of this kind of connected mode is: 1 can surge current suppression, makes surge current be unlikely to excessive other components and parts that burn; 2 detect On current, to make suitable action; 3 play anti-reverse effect, during the gate turn-on positive source of field effect transistor Q3, its conducting, instead then switch on power negative pole time circuit close, be unlikely to burn out circuit; 4 overtemperature protections; the temperature produced when electric current is excessive in circuit is high; the resistance of thermistor RT changes; the voltage of the grid of field effect transistor Q3 changes; the on state resistance of field effect transistor Q3 changes; feedback quantity changes, and sends and can control trigger signal closedown, and then play many-sided protective effect to circuit according to the setting of the chip that can control trigger signal.

Accompanying drawing explanation

Fig. 1 is that the circuit of embodiment connects schematic representation intention.

Embodiment

Be illustrated in figure 1 a kind of circuit connection diagram of protective circuit, comprise field effect transistor, the drain electrode of field effect transistor Q1 is connected with the input of transformer T respectively with the drain electrode of field effect transistor Q2, contact resistance R3 between the grid of field effect transistor Q1 and source electrode, contact resistance R4 between the grid of field effect transistor Q2 and source electrode, input signal connects the grid of field effect transistor Q1 by resistance R1, another input signal connects the grid of field effect transistor Q2 by resistance R2, the source electrode of field effect transistor Q1 is connected with the source electrode of field effect transistor Q2 and is connected with the source electrode of field effect transistor Q3 or drain, the drain electrode of field effect transistor Q3 or source ground, the grid of field effect transistor Q3 connects power end by resistance R5.The grid of described field effect transistor Q3 also connects power end by diode D, and the positive pole of diode D is connected with the grid of field effect transistor Q3.The grid of described field effect transistor Q3 also connects thermistor RT, the other end ground connection of thermistor RT.

The described input signal by resistance R1 is pulse signal, is pulse signal by the input signal of resistance R2, and by the pulse input signal of resistance R1 be alternately input by the pulse input signal of resistance R2.

Claims

1. a protective circuit, comprise field effect transistor, it is characterized in that, the drain electrode of field effect transistor Q1 is connected with the input of transformer T respectively with the drain electrode of field effect transistor Q2, contact resistance R3 between the grid of field effect transistor Q1 and source electrode, contact resistance R4 between the grid of field effect transistor Q2 and source electrode, input signal connects the grid of field effect transistor Q1 by resistance R1, another input signal connects the grid of field effect transistor Q2 by resistance R2, the source electrode of field effect transistor Q1 is connected with the source electrode of field effect transistor Q2 and is connected with the source electrode of field effect transistor Q3 or drain, the drain electrode of field effect transistor Q3 or source ground, the grid of field effect transistor Q3 connects power end by resistance R5.

2. protective circuit according to claim 1, is characterized in that, the grid of described field effect transistor Q3 also connects power end by diode D, and the positive pole of diode D is connected with the grid of field effect transistor Q3.

3. protective circuit according to claim 2, it is characterized in that, the grid of described field effect transistor Q3 also connects thermistor RT, the other end ground connection of thermistor RT.

4. protective circuit according to claim 1; it is characterized in that; the described input signal by resistance R1 is pulse signal, is pulse signal by the input signal of resistance R2, and by the pulse input signal of resistance R1 be alternately input by the pulse input signal of resistance R2.