Overvoltage protection circuit

Abstract

The utility model discloses an overvoltage protection circuit, which comprises a power management module, a detection module and a control module, the power supply management module is connected between an external power supply and the lamp and is used for controlling voltage output to the lamp; the input end of the detection module is connected between the output end of the power management module and the lamp and is used for detecting the output voltage of the power management module; the control module is connected between the output end of the detection module and the power management module; the control module can continuously send a turn-off signal to the power management module when the detection module detects that the power management module outputs overvoltage, so that the power management module keeps turn-off output; through the above structure, the power supply does not work in an over-voltage state repeatedly and circularly, the safety performance of the power supply is greatly improved, and the practicability is very good.

Description

Technical Field

[0001] The utility model relates to the field of power supply circuits and controller circuits, and in particular to an overvoltage protection circuit. Background Art

[0002] With the development of science and technology, switching power supplies have flourished in the electronics industry, and switching power supplies of various powers, currents, and output voltages have emerged in an endless stream. The output voltage range of the switching power supply is an issue that all products must strictly control and pay attention to; if the output voltage of the switching power supply is overvoltage, it will be very likely to burn out the load it carries. The overvoltage protection function currently used in the industry is basically to control the output voltage to a set value through the detection circuit and the control circuit after the output voltage is overvoltage. When the output voltage is lower than the set value, the protection circuit will no longer work until the next overvoltage occurs. This situation will be a cycle process, which will cause the switching power supply to work repeatedly in this state before the fault is eliminated, greatly reducing the product life. There is also a great possibility that the output device will be burned out due to the continuous circulation of overvoltage, causing serious burn-in; therefore, an overvoltage protection circuit is urgently needed to solve the above problems. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides an overvoltage protection circuit.

[0004] An embodiment of the utility model solves the technical problem by adopting a technical solution: an overvoltage protection circuit, including a power management module, a detection module and a control module;

[0005] The power management module is connected between the external power supply and the lamp, and is used to control the voltage output to the lamp;

[0006] The input end of the detection module is connected between the output end of the power management module and the lamp, and is used to detect the output voltage of the power management module;

[0007] The control module is connected between the output end of the detection module and the power management module;

[0008] The control module can continuously send a shutdown signal to the power management module when the detection module detects that the output of the power management module is over-voltage, so that the power management module keeps shutting down the output.

[0009] As one of the preferred embodiments of the utility model, the power management module includes a rectifier bridge DB1, capacitors EC1-EC3, capacitor C1, resistors R1-4, MOS tube Q1, diodes D1-3, transformer T1 and power chip U1. The input end of the rectifier bridge DB1 is respectively connected to L and N of the external power supply, and the output end of the rectifier bridge DB1 is respectively connected to the first end of the capacitor EC1, the first end of the resistor R1, the first end of the capacitor C1, the first end of the resistor R2 and the first end of the transformer T1. The second end of the resistor R1 is connected to the first pin of the power chip U1, the second end of the capacitor C1 and the second end of the resistor R2 are commonly connected to the first end of the diode D1, the second end of the diode D2 is respectively connected to the drain of the MOS tube Q1 and the second end of the transformer T1, the third end of the transformer T1 is respectively connected to the first end of the capacitor EC2 and the sixth end of the power chip U1 via the diode D2, and the MOS tube The gate of Q1 is connected to the fifth end of the power chip U1 via the resistor R3, the source of the MOS tube Q1 is respectively connected to the first end of the resistor R4 and the fourth end of the power chip U1, the fifth end of the transformer T1 is respectively connected to the first end of the capacitor EC3 and one end of the lamp via the diode D3, the sixth end of the transformer T1 is respectively connected to the second end of the capacitor EC3, the GNS end and the other end of the lamp, the second end of the capacitor EC1, the second end of the capacitor EC2, the fourth end of the transformer T1, the second end of the power chip U1, and the second end of the resistor R4 are commonly connected to the GND end.

[0010] As one of the preferred embodiments of the utility model, the detection module includes a voltage regulator tube ZD1 and a resistor R8, the first end of the voltage regulator tube ZD1 is connected between the output end of the power management module and the lamp, and the second end of the voltage regulator tube ZD1 is connected to the input end of the control module via the resistor R8.

[0011] As one of the preferred embodiments of the utility model, the control module includes resistors R5-7, a diode D4 and a thyristor Q2, the first end of the resistor R5 and the first end of the resistor R7 are connected to the output end of the detection module, the second end of the resistor R5 is respectively connected to the first end of the resistor R6 and the VCC end, the second end of the resistor R6 is connected to the input end of the thyristor Q2, the second end of the resistor R7 is connected to the control end of the thyristor Q2, and the output end of the thyristor Q2 is connected to the power management module via the diode D4.

[0012] As one of the preferred embodiments of the present utility model, an overvoltage protection circuit further includes a feedback isolation module connected between the detection module and the control module.

[0013] As one of the preferred embodiments of the utility model, the feedback isolation module includes an optical coupler U2, both ends of the light emitter of the optical coupler U2 are connected to the output end of the detection module, and both ends of the light receiver of the optical coupler U2 are connected to the input end of the control module respectively.

[0014] The beneficial effects of the utility model include: an overvoltage protection circuit, comprising a power management module, a detection module and a control module; the power management module is connected between an external power supply and a lamp, and is used to control the voltage output to the lamp; the input end of the detection module is connected between the output end of the power management module and the lamp, and is used to detect the output voltage of the power management module; the control module is connected between the output end of the detection module and the power management module; the control module can continuously send a shutdown signal to the power management module when the detection module detects that the output of the power management module is overvoltage, so that the power management module keeps shutting down the output; through the above structure, the power supply will not repeatedly operate in an overvoltage state, which greatly increases the safety performance of the power supply and has very good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0016] Figure 1 It is a principle block diagram of an overvoltage protection circuit;

[0017] Figure 2 The figure is a circuit schematic diagram of an overvoltage protection circuit. DETAILED DESCRIPTION

[0018] This section will describe in detail the specific embodiments of the utility model. The preferred embodiments of the utility model are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the utility model, but it cannot be understood as a limitation on the protection scope of the utility model.

[0019] In the description of the present utility model, the meaning of "more than" is more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0020] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] In the present invention, unless otherwise clearly defined, the words "set", "install", "connect" and the like should be understood in a broad sense, for example, they can be directly connected or indirectly connected through an intermediate medium; they can be fixedly connected or detachably connected or integrally formed; they can be mechanically connected; they can be the internal connection of two elements or the interaction relationship between two elements. Those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0022] Reference Figure 1 to Figure 2 , an overvoltage protection circuit, comprising a power management module 10, a detection module 20 and a control module 30;

[0023] The power management module 10 is connected between the external power source and the lamp, and is used to control the voltage output to the lamp;

[0024] The input end of the detection module 20 is connected between the output end of the power management module 10 and the lamp, and is used to detect the output voltage of the power management module 10;

[0025] The control module 30 is connected between the output end of the detection module 20 and the power management module 10;

[0026] The control module 30 may continue to send a shutdown signal to the power management module 10 when the detection module 20 detects that the output of the power management module 10 is over-voltage, so that the power management module 10 keeps shutting down the output.

[0027] In the present invention, the voltage input by the external power supply is rectified and filtered to provide voltage for the transformer T1, and then the transformer T1 performs power conversion. The power chip U1 is responsible for the management of the output voltage, specifically:

[0028] (1) In the power management module 10, the power management module 10 includes a rectifier bridge DB1, capacitors EC1-EC3, capacitor C1, resistors R1-4, MOS tube Q1, diodes D1-3, transformer T1 and a power chip U1. The input end of the rectifier bridge DB1 is respectively connected to L and N of the external power supply. The output end of the rectifier bridge DB1 is respectively connected to the first end of the capacitor EC1, the first end of the resistor R1, the first end of the capacitor C1, the first end of the resistor R2 and the first end of the transformer T1. The second end of the resistor R1 is connected to the first pin of the power chip U1. The second end of the capacitor C1 and the second end of the resistor R2 are commonly connected to the first end of the diode D1. The second end of the diode D2 is respectively connected to the drain of the MOS tube Q1 and the drain of the transformer T1. The second end of the transformer T1 is connected to the first end of the capacitor EC2 and the sixth end of the power chip U1 via the diode D2, the third end of the transformer T1 is connected to the first end of the capacitor EC2 and the sixth end of the power chip U1 via the diode D2, the gate of the MOS tube Q1 is connected to the fifth end of the power chip U1 via the resistor R3, the source of the MOS tube Q1 is connected to the first end of the resistor R4 and the fourth end of the power chip U1, the fifth end of the transformer T1 is connected to the first end of the capacitor EC3 and one end of the lamp via the diode D3, the sixth end of the transformer T1 is connected to the second end of the capacitor EC3, the GNS end and the other end of the lamp, the second end of the capacitor EC1, the second end of the capacitor EC2, the fourth end of the transformer T1, the second end of the power chip U1, and the second end of the resistor R4 are connected to the GND end together.

[0029] (2) The input end of the detection module 20 is connected between the output end of the power management module 10 and the lamp. Preferably, the detection module 20 includes a voltage regulator tube ZD1 and a resistor R8. The first end of the voltage regulator tube ZD1 is connected between the output end of the power management module 10 and the lamp, and the second end of the voltage regulator tube ZD1 is connected to the input end of the control module 30 via the resistor R8.

[0030] (3) In the control module 30, the control module 30 includes resistors R5-7, a diode D4 and a thyristor Q2. The first end of the resistor R5 and the first end of the resistor R7 are connected to the output end of the detection module 20. The second end of the resistor R5 is connected to the first end of the resistor R6 and the VCC end respectively. The second end of the resistor R6 is connected to the input end of the thyristor Q2. The second end of the resistor R7 is connected to the control end of the thyristor Q2. The output end of the thyristor Q2 is connected to the power management module 10 via the diode D4.

[0031] (4) In another embodiment, a feedback isolation module 40 is further included that is connected between the detection module 20 and the control module 30; preferably, the feedback isolation module 40 includes an optocoupler U2, wherein the two ends of the light emitter of the optocoupler U2 are connected to the output end of the detection module 20, and the two ends of the light receiver of the optocoupler U2 are respectively connected to the input end of the control module 30.

[0032] (5) The working principle of the utility model is as follows: when the system is powered on and works normally, if the system output voltage exceeds the limit value at this time, the current through the voltage regulator tube ZD1 increases, and then through the resistor R8, the light-emitting system in the optocoupler U2 works; the other end of the optocoupler U2 detects that the light-emitting system is working and then turns on, and the VCC voltage provides a driving signal to the control end of the thyristor Q2 through the resistor R5 and the resistor R7. The thyristor Q2 starts to conduct, and the voltage of the third end of the power chip U1 is raised through the diode D4, and the power chip U1 stops working. At this time, the output voltage of the power management module 10 can be lower than the limit value, and the optocoupler U2 stops working, so that the control end of the thyristor Q2 is interrupted. At this time, the thyristor Q2 will continue to conduct, thereby locking the third end of the power chip U1, so that the entire system stops working until the power is turned on again for the second time, and finally the power supply will not repeatedly work in an overvoltage state, greatly increasing the power supply safety performance.

[0033] Of course, the present invention is not limited to the above-mentioned embodiments, and technicians familiar with the field may make equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications and substitutions are all included in the scope defined by the claims of this application.

Claims

1. An overvoltage protection circuit, characterized in that: It comprises a power management module (10), a detection module (20) and a control module (30); The power management module (10) is connected between the external power supply and the lamp, and is used to control the voltage output to the lamp; The input end of the detection module (20) is connected between the output end of the power management module (10) and the lamp, and is used to detect the output voltage of the power management module (10); The control module (30) is connected between the output end of the detection module (20) and the power management module (10); The control module (30) can continuously send a shutdown signal to the power management module (10) when the detection module (20) detects that the output of the power management module (10) is over-voltage, so that the power management module (10) keeps shutting down the output; The power management module (10) comprises a rectifier bridge DB1, capacitors EC1-EC3, capacitor C1, resistors R1-4, MOS tube Q1, diodes D1-3, transformer T1 and a power chip U1, wherein the input end of the rectifier bridge DB1 is respectively connected to L and N of an external power source, the output end of the rectifier bridge DB1 is respectively connected to the first end of the capacitor EC1, the first end of the resistor R1, the first end of the capacitor C1, the first end of the resistor R2 and the first end of the transformer T1, the second end of the resistor R1 is connected to the first pin of the power chip U1, the second end of the capacitor C1 and the second end of the resistor R2 are commonly connected to the first end of the diode D1, the second end of the diode D2 is respectively connected to the drain of the MOS tube Q1 and the drain of the transformer T1 The two ends are connected, the third end of the transformer T1 is connected to the first end of the capacitor EC2 and the sixth end of the power chip U1 respectively through the diode D2, the gate of the MOS tube Q1 is connected to the fifth end of the power chip U1 through the resistor R3, the source of the MOS tube Q1 is connected to the first end of the resistor R4 and the fourth end of the power chip U1 respectively, the fifth end of the transformer T1 is connected to the first end of the capacitor EC3 and one end of the lamp respectively through the diode D3, the sixth end of the transformer T1 is connected to the second end of the capacitor EC3, the GNS end and the other end of the lamp respectively, the second end of the capacitor EC1, the second end of the capacitor EC2, the fourth end of the transformer T1, the second end of the power chip U1, and the second end of the resistor R4 are commonly connected to the GND end.

2. An overvoltage protection circuit according to claim 1, characterized in that: The detection module (20) comprises a voltage regulator tube ZD1 and a resistor R8, wherein a first end of the voltage regulator tube ZD1 is connected between an output end of the power management module (10) and the lamp, and a second end of the voltage regulator tube ZD1 is connected to an input end of the control module (30) via the resistor R8.

3. The overvoltage protection circuit according to claim 1, characterized in that: The control module (30) comprises resistors R5-7, a diode D4 and a thyristor Q2, wherein the first end of the resistor R5 and the first end of the resistor R7 are connected to the output end of the detection module (20), the second end of the resistor R5 is connected to the first end of the resistor R6 and the VCC end respectively, the second end of the resistor R6 is connected to the input end of the thyristor Q2, the second end of the resistor R7 is connected to the control end of the thyristor Q2, and the output end of the thyristor Q2 is connected to the power management module (10) via the diode D4.

4. The overvoltage protection circuit according to claim 1, characterized in that: It also includes a feedback isolation module (40) connected between the detection module (20) and the control module (30).

5. An overvoltage protection circuit according to claim 4, characterized in that: The feedback isolation module (40) comprises an optical coupler U2, the two ends of the light emitter of the optical coupler U2 are connected to the output end of the detection module (20), and the two ends of the light receiver of the optical coupler U2 are respectively connected to the input end of the control module (30).

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