CN214674343U

CN214674343U - Reverse connection prevention and overvoltage prevention protection circuit

Info

Publication number: CN214674343U
Application number: CN202120722526.6U
Authority: CN
Inventors: 叶顺德
Original assignee: Dongguan Aolei Mobile Lighting Equipment Co Ltd
Current assignee: Dongguan Aolei Mobile Lighting Equipment Co Ltd
Priority date: 2021-04-09
Filing date: 2021-04-09
Publication date: 2021-11-09
Anticipated expiration: 2031-04-09

Abstract

The utility model relates to an prevent reverse connection and prevent excessive pressure protection circuit, the grid of NMOS pipe Q3 passes through resistance R1 and connects the positive input end of power, the drain electrode of NMOS pipe Q3 connects the negative input end of power, the source electrode of NMOS pipe Q3 connects the negative output end of power; the base electrode of the PNP triode Q1 is connected with one end of a resistor R3 and the negative electrode of a voltage-stabilizing diode D1 through a resistor R4, the other end of the resistor R3 is connected with the emitter electrode of the PNP triode Q1 and the source electrode of a PMOS tube Q2, the positive electrode of the voltage-stabilizing diode D1 is connected with the output end of the negative electrode of a power supply and one end of the resistor R5, the other end of the resistor R5 is connected with the grid electrode of the PMOS tube Q2 and the collector electrode of the PNP triode Q1, a resistor R6 is connected between the grid electrode and the source electrode of the PMOS tube Q2, and the drain electrode of the PMOS tube Q2 is connected with the output end of the positive electrode of the power supply. The utility model discloses too much energy of consumption can not appear on protection circuit, realized the reversal and excessive pressure duplicate protection, the good reliability.

Description

Reverse connection prevention and overvoltage prevention protection circuit

Technical Field

The utility model belongs to the technical field of the protection circuit, a prevent reverse connection and prevent overvoltage crowbar is related to.

Background

In the process of supplying power to the direct-current power supply equipment through the direct-current power supply, if the anode and the cathode of the power supply are reversely connected, the equipment cannot work if the anode and the cathode of the power supply are connected, and the equipment can be burnt and damaged if the anode and the cathode of the power supply are reversely connected, so that a positive and reverse connection protection circuit is needed.

In the prior art, a forward diode is connected in series with an input end of a positive power supply, and the forward conduction and reverse cut-off characteristics of the diode are utilized. Under normal conditions, the diode is conducted, and the circuit board works. When the power supply is reversely connected, the diode is cut off, the power supply cannot form a loop, and no reverse current flows in the circuit board, so that the problem of reverse connection of the power supply is effectively protected. However, this solution has the following drawbacks: 1. energy is consumed on the diode, so that energy loss is caused; 2. the tube voltage drop limits the extent of discharge of the battery.

In addition, if the circuit performance parameters of the dc power supply change or fail, or the battery performance in the dc power supply changes, the output dc voltage is easily increased, and the operation of the subsequent load circuit is also easily affected, even the load circuit is burned. Therefore, the overvoltage prevention function should be designed on the basis of preventing reverse connection, so that the stability and reliability of the direct-current power supply can be ensured.

Disclosure of Invention

An object of the utility model is to prior art not enough, provide an prevent reverse connection and prevent overvoltage crowbar to solve current based on the diode prevent reverse connection circuit and will consume the energy, cause energy loss, and the pipe drop has restricted the problem of the degree of discharge of battery.

In order to achieve the above purpose, the utility model adopts the following technical scheme: an anti-reverse connection overvoltage protection circuit comprises a PNP triode Q1, a PMOS tube Q2 and an NMOS tube Q3, wherein the grid electrode of the NMOS tube Q3 is connected with the positive input end of a power supply through a resistor R1, the drain electrode of the NMOS tube Q3 is connected with the negative input end of the power supply, and the source electrode of the NMOS tube Q3 is connected with the negative output end of the power supply; PNP triode Q1's base passes through resistance R4 connecting resistance R3 one end, zener diode D1 negative pole, PNP triode Q1's projecting pole, PMOS pipe Q2 source are connected to the resistance R3 other end, power negative pole output and resistance R5 one end are connected to zener diode D1 positive pole, PMOS pipe Q2 grid, PNP triode Q1 collecting electrode are connected to the resistance R5 other end, connecting resistance R6 between PMOS pipe Q2's grid and the source, the anodal output of power is connected to PMOS pipe Q2 drain electrode, connect load between anodal output of power, the negative output of power.

Preferably, a fuse F is connected in series between the positive input end of the power supply and the source electrode of the PMOS transistor Q2.

Preferably, an RC hot plug spike absorption circuit formed by serially connecting a resistor R2 and a capacitor C1 is connected between the positive input end and the negative input end of the power supply.

Preferably, the source of the NMOS transistor Q3 is further connected to the positive electrode of the zener diode D2, and the gate of the NMOS transistor Q3 is further connected to the positive electrode and the negative electrode of the zener diode D2.

The utility model has the advantages that:

the utility model discloses based on PNP triode, PMOS pipe, NMOS pipe design prevent direct current power supply reversal and excessive pressure's protection circuit, because MOS pipe work is at on-off state, too much energy of consumption on protection circuit can not appear, realized reversal and excessive pressure duplicate protection. Meanwhile, a fuse and an RC peak absorption circuit are designed at the input end of the circuit, so that the reliability of the circuit is further improved.

Drawings

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

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

In the embodiments of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly, e.g., as fixed or detachable connections or as an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

As shown in fig. 1, an anti-reverse connection and overvoltage protection circuit includes a PNP triode Q1, a PMOS transistor Q2, and an NMOS transistor Q3, wherein a gate of the NMOS transistor Q3 is connected to a positive input terminal of a power supply through a resistor R1, a drain of the NMOS transistor Q3 is connected to a negative input terminal of the power supply, and a source of the NMOS transistor Q3 is connected to a negative output terminal of the power supply; the base electrode of the PNP triode Q1 is connected with one end of a resistor R3 and the negative electrode of a voltage-stabilizing diode D1 through a resistor R4, the other end of the resistor R3 is connected with the emitter electrode of the PNP triode Q1 and the source electrode of a PMOS tube Q2, the positive electrode of the voltage-stabilizing diode D1 is connected with the negative electrode output end of a power supply and one end of the resistor R5, the other end of the resistor R5 is connected with the grid electrode of the PMOS tube Q2 and the collector electrode of the PNP triode Q1, a resistor R6 is connected between the grid electrode and the source electrode of the PMOS tube Q2, the drain electrode of the PMOS tube Q2 is connected with the positive electrode output end of the power supply, and a load is connected between the positive electrode output end and the negative electrode output end of the power supply.

In this embodiment, a fuse F is connected in series between the positive input terminal of the power supply and the source of the PMOS transistor Q2, so as to prevent the whole circuit from being burned out due to overvoltage and overcurrent.

In this embodiment, an RC hot plug spike absorption circuit formed by serially connecting a resistor R2 and a capacitor C1 is connected between the positive input end and the negative input end of the power supply, and is used for absorbing spike pulses on the power supply voltage to protect the circuit.

In this embodiment, the source of the NMOS transistor Q3 is further connected to the positive electrode of the zener diode D2, the gate of the NMOS transistor Q3 is further connected to the positive electrode and the negative electrode of the zener diode D2, and the NMOS transistor Q3 can be protected by the gate of the NMOS transistor D2 against burning.

The utility model discloses a theory of operation is:

when the power is properly turned on, the current flows from Vin to the load and then to GND through the NMOS transistor Q3. The ground loop is switched on by the body diode of the NMOS transistor Q3 just after power-on, and the MOS transistor is subsequently switched on because Vgs is greater than the Vgsth threshold voltage. When the power supply is connected reversely, the body diode is not conducted, the voltage of Vgs cannot meet the requirement, the NMOS tube is not conducted, a current loop does not exist in the circuit, the circuit is broken, the load does not work, the load cannot be burned out, and protection is achieved. It should be noted that when the power supply is normally on, the current in the circuit is from S to D. Normally, Vgs can not be larger than the maximum withstand voltage value of Vgs of the NMOS tube, so that a voltage stabilizing tube D2 is bridged over the Vgs of the NMOS tube Q3 to prevent burning.

Meanwhile, when Vin normally inputs voltage, the voltage regulator tube D1 has no reverse breakdown, and the currents of R3 and R4 are basically 0. Vbe =0 for the PNP transistor, i.e. the PNP transistor is non-conductive. Vgs of the PMOS transistor Q2 is determined by voltage division of resistors R5 and R6, and the PMOS transistor is conducted, namely, a power supply works normally. When Vin input is larger than normal input voltage, Vin is larger than Vbr, the voltage regulator tube D1 is broken down, and the voltage on the voltage regulator tube D1 is Vbr. The PNP triode Q1 is conducted, VCE is approximately equal to 0, namely Vgs of the PMOS tube is approximately equal to 0, the PMOS tube is not conducted, the circuit is broken, and overvoltage protection is realized.

The above-mentioned embodiments are only one of the preferred embodiments of the present invention, and the ordinary changes and substitutions performed by those skilled in the art within the technical scope of the present invention should be included in the protection scope of the present invention.

Claims

1. The utility model provides a prevent reverse connection and prevent overvoltage crowbar which characterized in that: the PNP triode Q1, the PMOS tube Q2 and the NMOS tube Q3 are included, the grid electrode of the NMOS tube Q3 is connected with the positive electrode input end of a power supply through a resistor R1, the drain electrode of the NMOS tube Q3 is connected with the negative electrode input end of the power supply, and the source electrode of the NMOS tube Q3 is connected with the negative electrode output end of the power supply; PNP triode Q1's base passes through resistance R4 connecting resistance R3 one end, zener diode D1 negative pole, PNP triode Q1's projecting pole, PMOS pipe Q2 source are connected to the resistance R3 other end, power negative pole output and resistance R5 one end are connected to zener diode D1 positive pole, PMOS pipe Q2 grid, PNP triode Q1 collecting electrode are connected to the resistance R5 other end, connecting resistance R6 between PMOS pipe Q2's grid and the source, the anodal output of power is connected to PMOS pipe Q2 drain electrode, connect load between anodal output of power, the negative output of power.

2. An anti-reverse connection and anti-overvoltage protection circuit according to claim 1, characterized in that: and a fuse F is connected between the positive input end of the power supply and the source electrode of the PMOS tube Q2 in series.

3. An anti-reverse connection and anti-overvoltage protection circuit according to claim 1, characterized in that: and an RC hot plug spike absorption circuit formed by serially connecting a resistor R2 and a capacitor C1 is connected between the positive input end and the negative input end of the power supply.

4. An anti-reverse connection and anti-overvoltage protection circuit according to claim 1, characterized in that: the source electrode of the NMOS transistor Q3 is further connected with the anode of a voltage stabilizing diode D2, and the grid electrode of the NMOS transistor Q3 is further connected with the anode and the cathode of a voltage stabilizing diode D2.