CN212572079U

CN212572079U - Reverse connection and overvoltage protection circuit applied to transmitter

Info

Publication number: CN212572079U
Application number: CN202021535957.3U
Authority: CN
Inventors: 李楠; 陈恒; 李森; 刘少华; 王驰
Original assignee: Xijing University
Current assignee: Xijing University
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2021-02-19
Anticipated expiration: 2030-07-29

Abstract

The reverse connection and overvoltage protection circuit applied to the transmitter comprises an MOS transistor Q1, wherein the source electrode of the MOS transistor Q1 is connected with the anode of a direct-current power supply, the power supply is connected with a voltage stabilizing chip VR1 through a capacitor C1 and a capacitor C2, the drain electrode of an MOS tube Q1 is connected with a resistor R2 and a capacitor C3, the 1 pin, the 2 pin and the 3 pin of a voltage stabilizing source T1 are connected with the Vout end of the voltage stabilizing chip VR1, the cathode of a direct-current power supply and a slide rheostat R3, the 2 nd pin, the 3 rd pin, the 8 th pin, the 4 th pin and the 1 st pin of an operational amplifier Q2 are respectively connected with the slide rheostat R3 slide arm end, a resistor R4, the Vout end of the voltage stabilizing chip, the cathode of the direct-current power supply and a resistor R6, the other end of the resistor R6 is connected with the grid electrode of an MOS tube Q3, the drain electrode of the MOS tube Q3 is connected with one end of the source electrode of the MOS tube Q4, the other end of the resistor R7 is connected with the grid electrode of the MOS tube Q4, the positive electrode; the circuit has the advantages of simple circuit structure, high overvoltage protection precision and the like.

Description

Reverse connection and overvoltage protection circuit applied to transmitter

Technical Field

The utility model belongs to the technical field of the changer, concretely relates to be applied to transposition, overvoltage crowbar of changer.

Background

Due to the small size of the transmitter, the close input ends of the anode and the cathode of the power supply and the like, in the using process, the transmitter is sometimes subjected to reverse connection accidents due to misoperation; in addition, when some users use the transmitter, the quality of the connected input power supply is poor, overvoltage accidents are easy to happen, the transmitter is damaged due to the reasons, inconvenience in maintenance and replacement is brought, and economic loss is brought.

At present, the transmitters are provided with corresponding reverse connection and overvoltage protection circuits, but certain defects still exist in partial design schemes, for example, a reverse connection circuit part adopts a reverse connection diode for protection, although the mode has the advantages of low cost, simple line structure and the like, the scheme has low reliability, and breakdown accidents easily occur if high input voltage is met, so that the circuit structure of the transmitter is damaged. The overvoltage protection circuit part adopts a voltage stabilizing diode mode to perform overvoltage protection, and although the overvoltage protection circuit is simple in structure, the overvoltage protection precision is low, overvoltage threshold value setting cannot be performed, the flexibility is poor, and the reliability of a circuit is not high. Still carry out the reversal through the singlechip, overvoltage integration protection, though have advantages such as sampling accuracy height, still have shortcomings such as with high costs, design complicacy.

Disclosure of Invention

In order to overcome the defects of the prior art, the utility model aims to provide a reverse connection and overvoltage protection circuit applied to a transmitter, which has the advantages of simple circuit structure, high overvoltage protection precision and the like.

In order to achieve the above purpose, the utility model discloses the technical scheme who takes does:

a reverse connection and overvoltage protection circuit applied to a transmitter comprises an MOS tube Q1, wherein a source terminal of the MOS tube Q1 is connected with a positive terminal of a direct-current power supply, a capacitor C1, a capacitor C2 and a GND terminal, the other end of the capacitor C1 is connected with a Vin terminal of a voltage stabilizing chip VR1, the other end of the capacitor C2 is connected with a Vout terminal of the voltage stabilizing chip VR1, and the GND terminal of the voltage stabilizing chip VR1 is grounded; the drain end of the MOS transistor Q1 is connected with one end of a resistor R2 and a capacitor C3, the other ends of the resistor R2 and the capacitor C3 are connected with one end of a resistor R1 and the gate end of the MOS transistor Q1, and the other end of the resistor R1 is connected with the negative end of the direct-current power supply;

the Vout end of a voltage stabilizing chip VR1 is connected with the 1 pin end of a voltage stabilizing source T1, the 2 pin end of a voltage stabilizing source T1 is connected with the negative electrode end of a direct current power supply, the 3 pin end of a voltage stabilizing source T1 is connected with the 1 pin end of a sliding rheostat R3, the 2 pin end of a sliding rheostat R3 is connected with the negative electrode end of the direct current power supply, the sliding arm end of a sliding rheostat R3 is connected with the 2 nd pin of an operational amplifier Q2, the 3 rd pin of the operational amplifier Q2 is connected with one end of a resistor R4 and the 1 pin end of a sliding rheostat R5, the other end of the resistor R4 is connected with the drain electrode end of a MOS tube Q1, the sliding arm end of the sliding rheostat R5 is connected with the 2 pin end of the sliding rheostat R5 and the negative electrode end of the direct current power supply, the 8 pin of the operational amplifier Q2 is connected with the Vout end of the voltage stabilizing chip VR 9, the 4 th pin of the operational amplifier Q2 is connected with the negative electrode end of the direct current power supply, the 1 pin 1 of the operational amplifier Q2 is connected with one end of a resistor, the other end of the resistor R7 is connected with the grid end of the MOS tube Q4 and the negative end of the direct current power supply, the drain end of the MOS tube Q4 is connected with the positive end of the transducer, and the negative end of the transducer is connected with the source end of the MOS tube Q3 and the negative end of the direct current power supply.

The voltage stabilizing chip VR1 is in a direct insertion type MC7812CT, and the output voltage is 12V.

The voltage stabilizing source T1 is a three-end adjustable shunt reference voltage source with the model number of TL431AC, and the operational amplifier Q2 is with the model number of LM 358.

MOS pipe Q1, MOS pipe Q4 be SMD P channel MOS pipe, the model is: IRF 9530; MOS pipe Q3 is SMD N channel MOS pipe, and the model is: IRF 510.

The capacitor C1 and the capacitor C2 are electrolytic capacitors, and the parameter sizes are 470uF and 1000uF respectively.

The parameters of the resistor R1, the resistor R2, the slide rheostat R3, the resistor R4, the slide rheostat R5, the resistor R6 and the resistor R7 are 10K omega, 2K omega, 10K omega, 1K omega and 5K omega.

The utility model has the advantages that:

1. the utility model discloses a steady voltage source T1, slip resistor R3 carry out the voltage threshold and set for, compare in traditional zener diode's mode, have the voltage threshold and set for the precision height, adjust advantages such as convenient.

2. The utility model discloses a module such as Q2, constant voltage power supply VR1 are put to fortune, have guaranteed the accuracy of acquisition voltage, have improved overvoltage protection's reliability and stability.

3. The utility model discloses a MOS pipe Q1 carries out the transposition protection, compares in traditional transposition diode protection mode, has advantages such as the reliability is high, the security is high.

4. The utility model discloses whole circuit has advantages such as function diversification, with low costs, reliability height.

Drawings

Fig. 1 is a schematic circuit diagram of the present invention.

FIG. 2 is a schematic diagram of the current flow during normal operation of the transmitter.

FIG. 3 is a schematic diagram of the current flow in the event of an overvoltage event at the transmitter.

FIG. 4 is a schematic diagram of the operating principle of the transmitter in a reverse connection accident.

Detailed Description

The present invention will be further explained with reference to the drawings and examples.

Referring to fig. 1, the reverse connection and overvoltage protection circuit applied to the transmitter comprises an MOS transistor Q1, wherein a source terminal of the MOS transistor Q1 is connected with a positive terminal of a direct-current power supply, a capacitor C1, a capacitor C2 and a GND terminal, the other end of the capacitor C1 is connected with a Vin terminal of a voltage stabilization chip VR1, the other end of the capacitor C2 is connected with a Vout terminal of the voltage stabilization chip VR1, and the GND terminal of the voltage stabilization chip VR1 is grounded; the drain end of the MOS transistor Q1 is connected with one end of a resistor R2 and a capacitor C3, the other ends of the resistor R2 and the capacitor C3 are connected with one end of a resistor R1 and the gate end of the MOS transistor Q1, and the other end of the resistor R1 is connected with the negative end of the direct-current power supply;

The utility model discloses a theory of operation does:

as shown in fig. 1 and fig. 2, in order to ensure the reliability of the circuit operation, a voltage regulation chip VR1 is used for performing 12V regulated output, and the voltage output supplies power to a regulated power supply T1 and an operational amplifier Q2.

When the circuit normally works, current flows into the source terminal of the MOS transistor Q1 from the positive pole of the power supply, because the voltage Vgs at the two ends of the grid and the source of the MOS transistor Q1 is smaller than 0 at the moment, the MOS transistor Q1 is in a conducting state, and the current flows through the MOS transistor Q4 from the positive pole of the direct current power supply, and similarly, because the voltage Vgs at the two ends of the grid and the source of the MOS transistor Q4 is smaller than 0, the MOS transistor Q4 is conducted, and the current flows into the negative pole end of the direct current power supply after flowing through the transmitter to supply power for the transmitter module.

(1) Overvoltage protection working principle:

as shown in fig. 3, in order to ensure the safety, reliability and stability of the overvoltage protection, voltage processing is performed by using a voltage regulator T1 and a sliding varistor R3, an output voltage of the voltage regulator is used as a reference voltage of an operational amplifier Q2, voltage division processing is performed by using a resistor R4 and the sliding varistor R5, the output voltage of the voltage regulator is used as a sampling voltage of an operational amplifier Q2, when a sampling voltage of a pin 3 of an operational amplifier Q2 is greater than a reference voltage of a pin 2, a pin 1 of the operational amplifier Q2 performs high-level output, and when a voltage of the pin 3 of the operational amplifier Q2 is less than the reference voltage of the pin 2, a pin 1 of the operational amplifier performs low-level output.

Assuming that the maximum working voltage of the transmitter is 15V, the maximum sampling voltage of the sliding rheostat R5 is 5V after voltage division processing, and the reference voltage of the operational amplifier Q2 needs to be set to be 5V through the regulating voltage regulator T1 and the sliding rheostat R3. Dividing the slide rheostat R3 into a 1-pin resistor R3(1) and a 2-pin resistor R3(2) by taking the slide arm end of the slide rheostat R3 as a dividing point (wherein R3(1) + R3(2) ═ R3)

Because:

obtaining by solution: r3(2) ═ 5K Ω; r3(1) ═ 10-5 ═ 5K Ω

According to the formula, the reference voltage of the operational amplifier Q2 is 5V, the maximum sampling voltage is 5V, when the working voltage of the transmitter is larger than 15V, due to the voltage stabilizing effect of the voltage stabilizing chip VR1 and the voltage stabilizing source T1, the sampling voltage is kept unchanged at 5V, but the sampling voltage is larger than 5V, so that the 1 pin end of the operational amplifier Q2 carries out high-level output, at the moment, the voltage of the grid electrode and the voltage of the source electrode of the MOS tube Q3 are larger than the conducting voltage of the MOS tube, the MOS tube Q3 is in the conducting state, due to the small internal resistance of the MOS tube Q3, the voltage division is small, the voltage of the source electrode of the MOS tube Q4 is almost reduced to 0, at the moment, the MOS tube Q4 is turned off, and the two ends of the.

(2) Reverse connection protection working principle:

as shown in fig. 4, when the dc power supply is reverse-connected, since the voltage at the gate of the MOS transistor Q1 is the power supply voltage, the voltage at the source is 0V, and the voltage Vgs at the gate and the source is greater than 0, the MOS transistor Q1 is in an off state, the circuit stops working, and performs corresponding reverse-connection protection.

Claims

1. The utility model provides an it connects, overvoltage crowbar to be applied to changer, includes MOS pipe Q1, its characterized in that: a source terminal of the MOS transistor Q1 is connected with a positive terminal of a direct-current power supply, a capacitor C1, a capacitor C2 and a GND terminal, the other end of the capacitor C1 is connected with a Vin terminal of a voltage stabilizing chip VR1, the other end of the capacitor C2 is connected with a Vout terminal of a voltage stabilizing chip VR1, and the GND terminal of the voltage stabilizing chip VR1 is grounded; the drain end of the MOS transistor Q1 is connected with one end of a resistor R2 and a capacitor C3, the other ends of the resistor R2 and the capacitor C3 are connected with one end of a resistor R1 and the gate end of the MOS transistor Q1, and the other end of the resistor R1 is connected with the negative end of the direct-current power supply;

2. The reverse connection, overvoltage protection circuit for a transmitter of claim 1 wherein: the voltage stabilizing chip VR1 is in a direct insertion type MC7812CT, and the output voltage is 12V.

3. The reverse connection, overvoltage protection circuit for a transmitter of claim 1 wherein: the voltage stabilizing source T1 is a three-end adjustable shunt reference voltage source with the model number of TL431AC, and the operational amplifier Q2 is with the model number of LM 358.

4. The reverse connection, overvoltage protection circuit for a transmitter of claim 1 wherein: MOS pipe Q1, MOS pipe Q4 be SMD P channel MOS pipe, the model is: IRF 9530; MOS pipe Q3 is SMD N channel MOS pipe, and the model is: IRF 510.

5. The reverse connection, overvoltage protection circuit for a transmitter of claim 1 wherein: the capacitor C1 and the capacitor C2 are electrolytic capacitors, and the parameter sizes are 470uF and 1000uF respectively.

6. The reverse connection, overvoltage protection circuit for a transmitter of claim 1 wherein: the parameters of the resistor R1, the resistor R2, the slide rheostat R3, the resistor R4, the slide rheostat R5, the resistor R6 and the resistor R7 are 10K omega, 2K omega, 10K omega, 1K omega and 5K omega.