Overvoltage protection circuit

Abstract

The utility model discloses an overvoltage protection circuit, which comprises a resistor R102, a resistor R103, a resistor R106, a resistor R109, a resistor R110, a voltage-regulator tube ZD100, a triode Q100, a triode Q101 and a voltage-regulator triode U100, one end of the resistor R102 is connected with a power supply end Vbus, the other end of the resistor R102 is electrically connected with a cathode of the voltage-regulator triode U100 through the resistor R103, an anode of the voltage-regulator triode U100 is grounded, and the other end of the resistor R102 is electrically connected with a cathode of the voltage-regulator triode U100 through the triode Q101. And one end of the resistor R106 is connected with a power supply end Vbus, and the other end of the resistor R106 is grounded through the resistor R107. The overvoltage protection circuit disclosed by the utility model can protect a power supply, can protect the power supply from being damaged when abnormal high voltage enters, can normally operate a load when the voltage enters a normal range, and has the advantages of low cost, high practicability, simple structure and the like.

Description

Technical Field

[0001] The utility model belongs to the technical field of overvoltage protection, and in particular relates to an overvoltage protection circuit. Background Art

[0002] Since the industrial voltages of different countries are different, and some countries have higher industrial voltages, in order to prevent the power supply from being damaged when the voltage is too high, an overvoltage protection circuit is added to the power input to prevent the input voltage from being too high, causing the power MOS tube to explode. Utility Model Content

[0003] The main purpose of the utility model is to provide an overvoltage protection circuit, which can protect the power supply. When abnormal high voltage enters, the power supply can be protected from damage. When the voltage enters the normal range, the load can operate normally. It has the advantages of low cost, high practicality and simple structure.

[0004] In order to achieve the above purpose, the utility model provides an overvoltage protection circuit, including a resistor R102, a resistor R103, a resistor R106, a resistor R109, a resistor R110, a voltage regulator ZD100, a transistor Q100, a transistor Q101 and a voltage regulator transistor U100, wherein:

[0005] One end of the resistor R102 is connected to the power supply terminal Vbus and the other end of the resistor R102 is electrically connected to the cathode of the voltage-stabilizing transistor U100 through the resistor R103, the anode of the voltage-stabilizing transistor U100 is grounded, one end of the resistor R106 is connected to the power supply terminal Vbus and the other end of the resistor R106 is grounded through the resistor R107, and the other end of the resistor R106 is also electrically connected to the control end of the voltage-stabilizing transistor U100;

[0006] The emitter of the transistor Q100 is electrically connected to the common terminal of the resistor R102 and the resistor R103, and the base of the transistor Q100 is electrically connected to the cathode of the voltage-stabilizing transistor U100. The collector of the transistor Q100 is grounded through the resistor R109 and the resistor R110 in sequence. The anode of the voltage-stabilizing transistor ZD100 is grounded and the cathode of the voltage-stabilizing transistor ZD100 is electrically connected to the emitter of the transistor Q100. The base of the transistor Q101 is electrically connected to the common terminal of the transistor R109 and the resistor R110.

[0007] As a further preferred technical solution of the above technical solution, the collector of the transistor Q101 is connected to the feedback pin FB of the control chip IC.

[0008] As a further preferred technical solution of the above technical solution, the emitter of the transistor Q101 is grounded.

[0009] As a further preferred technical solution of the above technical solution, a capacitor C100 is connected in parallel to both ends of the resistor R107.

[0010] As a further preferred technical solution of the above technical solution, the power supply terminal Vbus is a high voltage.

[0011] The beneficial effects of the utility model are:

[0012] After the power is turned on, VBus has a DC high voltage after rectification. Since the base (control end) reference voltage of the voltage stabilizing transistor U100 is 2.5V, the voltage is divided by R106 and R107 to determine the upper limit of the VBus overvoltage protection voltage. When VBus exceeds the set voltage upper limit, the reverse voltage of the U100 voltage stabilizing tube cannot reach balance. When the VBus voltage passes through R102, R103, and U100 to form a loop, the transistor Q100 is conducted due to the base current. VBus flows through the voltage regulator ZD100, R102, and R103, and then flows to the R109 resistor through the transistor Q100. The Q101 transistor is divided by the R109 and R110 resistors. The base current of Q101 conducts the voltage of the Q101 reflector to the collector and then to the ground, thus forming a loop. Since the emitter of the Q101 transistor is connected to the FB pin of the IC, the voltage of the FB pin is pulled to the ground, the FB voltage is 0, the IC does not work, and the power supply has no output. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The utility model discloses a circuit diagram of an overvoltage protection circuit. DETAILED DESCRIPTION

[0014] The following description is used to disclose the utility model so that those skilled in the art can implement the utility model. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the utility model defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the utility model.

[0015] The utility model discloses an overvoltage protection circuit. The specific embodiments of the utility model are further described below in conjunction with preferred embodiments.

[0016] In the embodiments of the present invention, those skilled in the art will note that the power supply terminal and the like involved in the present invention may be regarded as prior art.

[0017] Preferred embodiments.

[0018] like Figure 1 As shown, the utility model discloses an overvoltage protection circuit, including a resistor R102, a resistor R103, a resistor R106, a resistor R109, a resistor R110, a voltage regulator ZD100, a transistor Q100, a transistor Q101 and a voltage regulator transistor U100, wherein:

[0019] One end of the resistor R102 is connected to the power supply terminal Vbus and the other end of the resistor R102 is electrically connected to the cathode of the voltage-stabilizing transistor U100 through the resistor R103, the anode of the voltage-stabilizing transistor U100 is grounded, one end of the resistor R106 is connected to the power supply terminal Vbus and the other end of the resistor R106 is grounded through the resistor R107, and the other end of the resistor R106 is also electrically connected to the control end of the voltage-stabilizing transistor U100;

[0020] The emitter of the transistor Q100 is electrically connected to the common terminal of the resistor R102 and the resistor R103, and the base of the transistor Q100 is electrically connected to the cathode of the voltage-stabilizing transistor U100. The collector of the transistor Q100 is grounded through the resistor R109 and the resistor R110 in sequence. The anode of the voltage-stabilizing transistor ZD100 is grounded and the cathode of the voltage-stabilizing transistor ZD100 is electrically connected to the emitter of the transistor Q100. The base of the transistor Q101 is electrically connected to the common terminal of the transistor R109 and the resistor R110.

[0021] Specifically, the collector of the transistor Q101 is connected to the feedback pin FB of the control chip IC.

[0022] More specifically, the emitter of the transistor Q101 is grounded.

[0023] Furthermore, the two ends of the resistor R107 are connected in parallel with a capacitor C100.

[0024] Furthermore, the power supply terminal Vbus is a high voltage.

[0025] For this utility model:

[0026] The utility model adopts the following overvoltage protection circuit. With the above structure, the utility model has the following advantages: after the power supply is powered on, VBus has a DC high voltage after rectification. Since the base (control end) reference voltage of the voltage stabilizing transistor U100 is 2.5V, the upper limit of the VBus overvoltage protection voltage is determined by voltage division through R106 and R107. When VBus exceeds the set voltage upper limit, the reverse voltage of the U100 voltage stabilizing tube cannot reach balance, and the VBus voltage passes through R102, R103, and U100 to form a loop. When the circuit is turned on, the base current of transistor Q100 is turned on, and VBus flows to the R109 resistor through the voltage-regulating tube ZD100, R102, and R103. The Q101 transistor is divided by the R109 and R110 resistors, and the base current of Q101 makes the Q101 reflector voltage turn on to the collector to the ground, forming a loop. Since the emitter of Q101 transistor is connected to the FB pin of IC, the voltage of the FB pin is pulled to the ground, the FB voltage is 0, the IC does not work, and the power supply has no output.

[0027] The utility model can protect the power supply from being damaged when abnormal high voltage enters, and the load can operate normally when the voltage enters the normal range. The utility model has the advantages of low cost, high practicality and simple structure.

[0028] It is worth mentioning that the technical features such as the power supply terminal involved in this utility model patent application should be regarded as the prior art. The specific structure, working principle and possible control method and spatial layout method of these technical features can be selected by conventional methods in the field, and should not be regarded as the invention point of this utility model patent. This utility model patent will not be further elaborated.

[0029] For those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present utility model should be included in the protection scope of the present utility model.

Claims

1. An overvoltage protection circuit, characterized in that: It includes resistor R102, resistor R103, resistor R106, resistor R109, resistor R110, voltage regulator ZD100, transistor Q100, transistor Q101 and voltage regulator transistor U100, wherein: One end of the resistor R102 is connected to the power supply terminal Vbus and the other end of the resistor R102 is electrically connected to the cathode of the voltage-stabilizing transistor U100 through the resistor R103, the anode of the voltage-stabilizing transistor U100 is grounded, one end of the resistor R106 is connected to the power supply terminal Vbus and the other end of the resistor R106 is grounded through the resistor R107, and the other end of the resistor R106 is also electrically connected to the control end of the voltage-stabilizing transistor U100; The emitter of the transistor Q100 is electrically connected to the common terminal of the resistor R102 and the resistor R103, and the base of the transistor Q100 is electrically connected to the cathode of the voltage-stabilizing transistor U100. The collector of the transistor Q100 is grounded through the resistor R109 and the resistor R110 in sequence. The anode of the voltage-stabilizing transistor ZD100 is grounded and the cathode of the voltage-stabilizing transistor ZD100 is electrically connected to the emitter of the transistor Q100. The base of the transistor Q101 is electrically connected to the common terminal of the transistor R109 and the resistor R110.

2. An overvoltage protection circuit according to claim 1, characterized in that: The collector of the transistor Q101 is connected to the feedback pin FB of the control chip IC.

3. An overvoltage protection circuit according to claim 2, characterized in that: The emitter of the transistor Q101 is grounded.

4. An overvoltage protection circuit according to claim 3, characterized in that: The two ends of the resistor R107 are connected in parallel with a capacitor C100 .

5. An overvoltage protection circuit according to claim 4, characterized in that: The power supply terminal Vbus is a high voltage.

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