CN215120107U - Power supply overvoltage protection circuit - Google Patents

Abstract

A power supply overvoltage protection circuit realizes that the voltage of an output end is zero when the input voltage exceeds a set normal value by the combined use of a voltage-regulator tube, a PNP type triode and a P channel Mosfet, and realizes the matching of different overvoltage thresholds and bearing currents by the model selection of the voltage-regulator tube and the P channel Mosfet. The circuit has the advantages of simple principle, low price and large borne current, and different voltage threshold values and bearing capacity requirements can be flexibly realized by simply replacing devices.

Description

Power supply overvoltage protection circuit

Technical Field

The invention belongs to the field of electricity, and particularly relates to an overvoltage protection circuit.

Background

An overvoltage protection circuit is a common function of a circuit board, and generally, the overvoltage protection circuit is designed by using a special chip. Typically, the currents carried by a dedicated chip are relatively small and the model is not usually well matched to the requirements.

Disclosure of Invention

The present disclosure provides a low cost overvoltage protection circuit that can have flexible voltage protection requirements and greater current carrying capability.

The present disclosure provides an overvoltage protection circuit, comprising: stabilivolt, PNP type triode, P channel Mosfet to and first resistance, second resistance, third resistance, wherein:

an end connection power input of first resistance with the projecting pole of PNP type triode, and the source electrode of P channel Mosfet, another termination the negative pole of stabilivolt and the one end of second resistance, another termination of second resistance PNP type triode's base, the collecting electrode of PNP type triode connect the one end of third resistance with the grid stage of P channel Mosfet, the drain junction power output of P channel Mosfet, the positive pole of stabilivolt and the other end ground connection of third resistance.

Further, the overvoltage threshold of the circuit is realized by adjusting the type of the voltage regulator tube.

Further, different current sizes are matched by changing the model of the P-channel Mosfet.

According to the overvoltage protection circuit, the voltage regulator tube, the PNP type triode and the P channel Mosfet are combined for use, so that when the input voltage exceeds a set normal value, the voltage of the output end is zero, and matching of different overvoltage thresholds and bearing currents can be achieved through type selection of the voltage regulator tube and the P channel Mosfet. Compared with the prior art, the beneficial effect of this disclosure is: the overvoltage protection circuit is simple in principle and low in price, different voltage requirements can be met by simply replacing devices, and the loaded current is large, so that the overvoltage protection circuit has remarkable advantages.

Drawings

The foregoing and other objects, features and advantages of the disclosure will be apparent from the following more particular descriptions of exemplary embodiments of the disclosure as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the disclosure.

Fig. 1 shows a circuit diagram according to an exemplary embodiment of the present disclosure.

Detailed Description

Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

As shown in fig. 1, an exemplary embodiment of a supply voltage protection circuit according to the present disclosure includes: the circuit comprises a resistor R1, a resistor R2, a resistor R3, a voltage regulator tube D1, a PNP type triode Q2 and a P-channel Mosfet Q1. One end of the resistor R1 is connected with the emitters of the power input terminals VCC _ in and Q2, the source of Q1, the other end is connected with the cathode of D1 and one end of R2, the other end of the resistor R2 is connected with the base of Q2, the collector of Q2 is connected with one end of R3 and the gate of Q1, and the drain of Q1 is connected with the power output terminal VCC _ out.

When the voltage of VCC _ in is smaller than the clamping voltage of D1, the base of Q2 and the collector of Q2 are equal, then Q2 is not conducted, then the voltage of the grid of Q1 is zero, because the voltage of the source of Q1 is larger than the voltage of the grid of Q1, then Q1 is conducted, namely VCC _ out has voltage output;

when the voltage VCC _ in is greater than the clamping voltage of D1, the voltage at one end of R2 is a fixed value, at this time, the base voltage of Q2 is less than the collector voltage of Q2, Q2 is conducted, and since Q2 is conducted, the source voltage of Q1 is equal to the gate voltage of Q1, so that Q1 is not conducted, and VCC _ out has no voltage output, thereby realizing overvoltage protection.

When the overvoltage threshold needs to be adjusted, the overvoltage threshold can be adjusted by adjusting the type of D1; by changing the model of the Q1, different current magnitudes can be matched; therefore, the circuit can flexibly realize the required threshold value and bearing capacity.

Therefore, in the exemplary power supply overvoltage protection circuit, when the input voltage is a normal set value, the voltage of the output end is equal to that of the input end; when the input voltage exceeds the set normal value, the output end voltage is zero. The circuit is simple in principle and low in price, different voltage requirements can be met by simply replacing devices, the current ratio of the load is large, and the circuit has remarkable advantages.

The foregoing is illustrative of the present invention and various modifications and changes in form or detail will readily occur to those skilled in the art based upon the teachings herein and the application of the principles and principles disclosed herein, which are to be regarded as illustrative rather than restrictive on the broad principles of the present invention.

Claims (3)

1. An overvoltage protection circuit, comprising: stabilivolt, PNP type triode, P channel Mosfet to and first resistance, second resistance, third resistance, wherein:

an end connection power input of first resistance with the projecting pole of PNP type triode, and the source electrode of P channel Mosfet, another termination the negative pole of stabilivolt and the one end of second resistance, another termination of second resistance PNP type triode's base, the collecting electrode of PNP type triode connect the one end of third resistance with the grid stage of P channel Mosfet, the drain junction power output of P channel Mosfet, the positive pole of stabilivolt and the other end ground connection of third resistance.

2. The overvoltage protection circuit of claim 1, wherein the overvoltage threshold of the circuit is achieved by adjusting the type of the regulator tube.

3. The overvoltage protection circuit of claim 1, wherein different current magnitudes are matched by changing a model of the P-channel Mosfet.

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