Overvoltage protection circuit and electrical equipment

Abstract

The embodiment of the utility model provides an overvoltage protection circuit and electrical equipment, and the circuit comprises a first switch unit which has a break-over voltage, and one end of the first switch unit is used for inputting a sampling voltage; the control end of the second switch unit is connected with the first switch unit; the control end of the third switch unit is connected with the second switch unit, and the first end of the third switch unit is grounded; the chip comprises an overvoltage protection port, and the overvoltage protection port is connected with the second end of the third switch unit; when the sampling voltage is greater than the conduction voltage, the first switch unit is conducted and drives the second switch unit to be conducted, the second switch unit drives the third switch unit to be conducted, and the overvoltage protection port generates an overvoltage protection signal. According to the overvoltage protection circuit provided by the embodiment of the invention, electronic components in the circuit can be prevented from being burnt out due to overhigh voltage, and the stability of the circuit can be improved, so that the safety of electrical equipment is improved.

Description

Overvoltage protection circuits and electrical equipment Technical Field

[0001] This application relates to the field of circuit technology, and in particular to an overvoltage protection circuit and electrical equipment. Background Technology

[0002] In a circuit, the power supply voltage fluctuates due to various factors. If the voltage is too high and left uncontrolled, it can exceed the maximum voltage limit of electronic components, damaging them and ultimately causing the entire electrical equipment to malfunction. Summary of the Invention

[0003] This application provides an overvoltage protection circuit and electrical device that can improve circuit stability.

[0004] This application provides an overvoltage protection circuit, including:

[0005] A first switching unit, the first switching unit having an on voltage, and one end of the first switching unit being used to input a sampling voltage;

[0006] The second switching unit is connected to the first switching unit;

[0007] The third switching unit has its control terminal connected to the second switching unit, and its first terminal is grounded.

[0008] The chip includes an overvoltage protection port, which is connected to the second terminal of the third switching unit;

[0009] When the sampling voltage is greater than the conduction voltage, the first switching unit is turned on and drives the second switching unit to turn on, the second switching unit drives the third switching unit to turn on, and the overvoltage protection port generates an overvoltage protection signal.

[0010] In some embodiments, the first switching unit includes a Zener diode, the reference electrode of which is used to input a sampling voltage, the anode of which is grounded, and the cathode of which is connected to the control terminal of the second switching unit.

[0011] In some embodiments, the second switching unit includes a transistor, the base of which is connected to the cathode of the Zener diode, the emitter of which is connected to a power supply, and the collector of which is connected to the control terminal of the third switching unit.

[0012] In some embodiments, the overvoltage protection circuit further includes a first diode and a first resistor, wherein the anode of the first diode is connected to the base of the transistor, and the first resistor is connected between the cathode of the first diode and the cathode of the Zener diode.

[0013] In some embodiments, the third switching unit includes a MOS transistor, the gate of which is connected to the collector of the transistor, the source of which is grounded, and the drain of which is connected to the overvoltage protection port of the chip.

[0014] In some embodiments, the overvoltage protection circuit further includes a second diode and a second resistor, wherein the cathode of the second diode is connected to the gate of the MOS transistor, and the second resistor is connected between the anode of the second diode and the collector of the transistor.

[0015] In some embodiments, the overvoltage protection circuit further includes a third resistor, one end of which is connected between the cathode of the second diode and the gate of the MOS transistor, and the other end of which is grounded.

[0016] In some embodiments, the overvoltage protection circuit further includes a sampling circuit connected between the power supply and the first switching unit, the sampling circuit being used to sample the power supply voltage to obtain the sampled voltage.

[0017] In some embodiments, the sampling circuit includes a fourth resistor, a fifth resistor, and a sixth resistor connected in series. The fourth resistor is connected to a power supply, the sixth resistor is grounded, and the first switching unit is connected between the fifth resistor and the sixth resistor.

[0018] This application also provides an electrical device including the overvoltage protection circuit described in any of the above embodiments.

[0019] In the overvoltage protection circuit of this application embodiment, when the sampled voltage is greater than the conduction voltage of the first switching unit, the first switching unit is turned on and drives the second switching unit to turn on, and the second switching unit drives the third switching unit to turn on. The overvoltage protection port of the chip generates an overvoltage protection signal, and the chip can then perform a protection action to protect the electronic components in the circuit from being burned out due to excessive voltage. Therefore, the stability of the circuit can be improved, thereby improving the safety of the electrical equipment. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 is a schematic diagram of the overvoltage protection circuit according to an embodiment of this application.

[0022] Figure 2 is a first example circuit diagram of the overvoltage protection circuit according to an embodiment of this application.

[0023] Figure 3 is a second example circuit diagram of the overvoltage protection circuit according to an embodiment of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] This application provides an overvoltage protection circuit for use in electrical equipment. The overvoltage protection circuit can activate protection when the input voltage of the circuit is too high, preventing electronic components in the circuit from being burned out due to excessive voltage. Therefore, it can improve circuit stability and thus enhance the safety of the electrical equipment.

[0026] Referring to Figure 1, which is a schematic diagram of the overvoltage protection circuit 100 according to an embodiment of this application, the overvoltage protection circuit 100 includes a first switching unit 10, a second switching unit 20, a third switching unit 30, and a chip 40. The first switching unit 10, the second switching unit 20, the third switching unit 30, and the chip 40 are connected in sequence.

[0027] One end of the first switching unit 10 is used to input the sampling voltage. In practical applications, the sampling voltage can be obtained by sampling the power supply voltage in the circuit or by sampling the voltage input from an external power source. The first switching unit 10 has an on-state voltage. When the sampling voltage is greater than the on-state voltage, the first switching unit 10 is turned on; when the sampling voltage is less than or equal to the on-state voltage, the first switching unit 10 is turned off.

[0028] Both the second switching unit 20 and the third switching unit 30 have a control terminal. In practical applications, both the second switching unit 20 and the third switching unit 30 can be three-port switching devices. The second switching unit 20 and the third switching unit 30 can be the same type of switching unit or different types of switching units. The control terminal of the second switching unit 20 is connected to the first switching unit 10. The control terminal of the third switching unit 30 is connected to the second switching unit 20. The third switching unit 30 also includes a first terminal and a second terminal, wherein the first terminal is grounded.

[0029] Chip 40 includes an overvoltage protection port, which is connected to the second terminal of the third switching unit 30. The overvoltage protection port of chip 40 can be used to generate an overvoltage protection signal. When an overvoltage protection signal is generated at the overvoltage protection port, chip 40 can perform a protection action, such as disconnecting the power input, disconnecting the core electronic components or modules in the circuit, disconnecting electronic components in the circuit with weak overvoltage resistance, or directly stopping chip 40 from working, etc.

[0030] In this embodiment, when the sampling voltage is greater than the turn-on voltage of the first switching unit 10, the first switching unit 10 turns on and drives the second switching unit 20 to turn on. The second switching unit 20 then drives the third switching unit 30 to turn on, and the overvoltage protection port of the chip 40 generates an overvoltage protection signal. At this time, the chip 40 can generate a protection action, protecting the electronic components in the circuit from being burned out due to excessive voltage. Therefore, the stability of the circuit can be improved, thereby enhancing the safety of the electrical equipment.

[0031] In some embodiments, referring to FIG2, FIG2 is a first circuit example diagram of an overvoltage protection circuit 100 according to an embodiment of the present application.

[0032] The first switching unit 10 includes a Zener diode U1. Zener diode U1 includes a reference electrode, an anode, and a cathode. The reference electrode of Zener diode U1 is used to input a sampling voltage, such as the sampling voltage IN-V. The anode of Zener diode U1 is grounded, for example, connected to the power ground PGND. The cathode of Zener diode U1 is connected to the control terminal of the second switching unit 20. In one example, the forward voltage of Zener diode U1 is 2.5V. In some embodiments, the cathode of Zener diode U1 is also connected to the power supply via a resistor R1, for example, connected to the power supply VDD via a resistor R1. In one example, the resistance value of resistor R1 can be 10kΩ. In practical applications, Zener diode U1 can be a Zener diode such as the TL431.

[0033] In some embodiments, the second switching unit 20 includes a transistor Q1. Transistor Q1 includes a base, an emitter, and a collector. The base of transistor Q1 is the control terminal of the second switching unit 20. The base of transistor Q1 is connected to the cathode of the Zener diode U1. The emitter of transistor Q1 is connected to a power supply, for example, to power supply VDD. The collector of transistor Q1 is connected to the control terminal of the third switching unit 30.

[0034] In some embodiments, the overvoltage protection circuit 100 further includes a first diode and a first resistor, such as a first diode D1 and a first resistor R2. The first diode D1 and the first resistor R2 are disposed between the base of transistor Q1 and the cathode of Zener diode U1. Specifically, the anode of the first diode D1 is connected to the base of transistor Q1, and the first resistor R2 is connected between the cathode of the first diode D1 and the cathode of Zener diode U1. In one example, the resistance value of the first resistor R2 can be 51kΩ.

[0035] In some embodiments, a resistor R3 may be connected in parallel between the base and emitter of transistor Q1. One end of resistor R3 is connected between the base of transistor Q1 and the anode of the first diode D1, and the other end is connected to the emitter of transistor Q1. In one example, the resistance value of resistor R3 may be 10kΩ.

[0036] In some embodiments, the third switching unit 30 includes a MOSFET Q2. The MOSFET Q2 includes a gate, a source, and a drain. The gate of the MOSFET Q2 serves as the control terminal of the third switching unit 30. The gate of the MOSFET Q2 is connected to the collector of the transistor Q1. The source of the MOSFET Q2 is grounded, for example, connected to the power ground PGND. The drain of the MOSFET Q2 is connected to the overvoltage protection port of the chip 40.

[0037] In some embodiments, the overvoltage protection circuit 100 further includes a second diode and a second resistor, such as a second diode D2 and a second resistor R4. The second diode D2 and the second resistor R4 are disposed between the gate of the MOSFET Q2 and the collector of the transistor Q1. Specifically, the cathode of the second diode D2 is connected to the gate of the MOSFET Q2, and the second resistor R4 is connected between the anode of the second diode D2 and the collector of the transistor Q1. In one example, the resistance value of the second resistor R4 can be 10kΩ.

[0038] In some embodiments, the overvoltage protection circuit 100 further includes a third resistor, such as a third resistor R5. The third resistor R5 is connected in parallel between the gate of the MOSFET Q2 and ground. One end of the third resistor R5 is connected between the cathode of the second diode D2 and the gate of the MOSFET Q2, and the other end of the third resistor R5 is grounded, for example, connected to the power ground PGND. The third resistor R5 can serve as a bleed resistor, forming a bleed path between the gate of the MOSFET Q2 and ground, allowing the gate of the MOSFET Q2 to discharge charge.

[0039] In some embodiments, chip 40 includes chip U2. Chip U2 includes multiple ports, such as eight ports including VDD, FB, OVP, GND, HV, NC, DRV, and CS. Among them, port FB can be used as an overvoltage protection port, and port FB is connected to the drain of MOSFET Q2.

[0040] In this embodiment, the overvoltage protection circuit 100 operates as follows:

[0041] If the sampling voltage IN-V is greater than the turn-on voltage of Zener diode U1 (e.g., 2.5V), Zener diode U1 turns on. The base of transistor Q1 is turned on by forming a bias current through the first diode D1 and the first resistor R2. The collector of transistor Q1 drives MOSFET Q2 to turn on through the second resistor R4 and the second diode D2. The overvoltage protection port FB of chip U2 is pulled low to the power ground PGND, and the overvoltage protection port FB generates a low-level signal, which is the overvoltage protection signal. Subsequently, chip U2 can generate protection action.

[0042] If the sampling voltage IN-V is not greater than the turn-on voltage of Zener diode U1 (e.g., 2.5V), Zener diode U1 will be turned off, the base of transistor Q1 will not form a bias current and will be turned off, the gate of MOSFET Q2 will lose its driving voltage and will be turned off, the overvoltage protection port FB of chip U2 will be disconnected from the power ground PGND, the overvoltage protection port FB will not generate a low-level signal, and thus will not trigger the protection action of chip U2, and chip U2 can work normally.

[0043] In some embodiments, referring to FIG3, FIG3 is a second circuit example diagram of the overvoltage protection circuit 100 of the present application.

[0044] The overvoltage protection circuit 100 also includes a sampling circuit 50. The sampling circuit 50 is connected between the power supply and the first switching unit 10. The power supply input voltage is HV, and the sampling circuit 50 is used to sample the power supply voltage HV to obtain a sampling voltage, such as the aforementioned sampling voltage IN-V.

[0045] In some embodiments, the sampling circuit 50 includes a fourth resistor, a fifth resistor, and a sixth resistor connected in series, such as the fourth resistor R6, the fifth resistor R7, and the sixth resistor R8. The fourth resistor R6 is connected to the power supply for inputting the power supply voltage HV. The sixth resistor R8 is grounded, for example, connected to the power supply ground PGND. A first switching unit 10 is connected between the fifth resistor R7 and the sixth resistor R8; for example, the reference terminal of the Zener diode U1 is connected between the fifth resistor R7 and the sixth resistor R8 to input the sampling voltage IN-V obtained by the sampling circuit 50. In one example, the resistance value of the fourth resistor R6 can be 1.4MΩ, the resistance value of the fifth resistor R7 can be 1.4MΩ, and the resistance value of the sixth resistor R8 can be 18kΩ.

[0046] In a practical example, the power supply voltage HV is 277V. Through a voltage divider formed by resistors R6, R7, and R8, the sampling voltage IN-V obtained between resistors R7 and R8 is 2.5V. When the power supply voltage HV exceeds 277V, the corresponding sampling voltage IN-V between R7 and R8 will be greater than 2.5V. Understandably, in practical applications, depending on the specific on-state voltage of the first switching unit 10, the magnitude of the sampling voltage IN-V can be changed by adjusting the resistance ratios of resistors R6, R7, and R8 to achieve a suitable overvoltage protection point.

[0047] In some embodiments, the sampling circuit 50 further includes a capacitor C, which is connected in parallel across the sixth resistor R8. That is, one end of capacitor C is connected between the fifth resistor R7 and the sixth resistor R8, and the other end is grounded, for example, connected to power ground PGND. Capacitor C can act as a filter to remove high-frequency interference signals in the power supply voltage HV. In one example, the capacitance value of capacitor C can be 2.2μF.

[0048] This application also provides an electrical device including the overvoltage protection circuit 100 of any of the above embodiments. The overvoltage protection circuit 100 can generate a protective action when the input voltage of the circuit is too high, protecting the electronic components in the circuit from being burned out due to excessive voltage, thus improving the stability of the circuit and thereby improving the safety of the electrical device.

[0049] In the description of this application, it should be understood that terms such as “first” and “second” are used only to distinguish similar objects and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0050] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0051] The overvoltage protection circuit and electrical equipment provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An overvoltage protection circuit, characterized in that, include: A first switching unit, the first switching unit having an on voltage, and one end of the first switching unit being used to input a sampling voltage; A second switching unit, the control terminal of which is connected to the first switching unit; a third switching unit, the control terminal of which is connected to the second switching unit, and the first terminal of which is grounded; a chip, the chip including an overvoltage protection port, the overvoltage protection port being connected to the second terminal of the third switching unit; wherein, when the sampling voltage is greater than the conduction voltage, the first switching unit conducts and drives the second switching unit to conduct, the second switching unit drives the third switching unit to conduct, and the overvoltage protection port generates an overvoltage protection signal.

2. The overvoltage protection circuit according to claim 1, characterized in that, The first switching unit includes a Zener diode, the reference electrode of which is used to input the sampling voltage, the anode of which is grounded, and the cathode of which is connected to the control terminal of the second switching unit.

3. The overvoltage protection circuit according to claim 2, characterized in that, The second switching unit includes a transistor, the base of which is connected to the cathode of the Zener diode, the emitter of which is connected to a power supply, and the collector of which is connected to the control terminal of the third switching unit.

4. The overvoltage protection circuit according to claim 3, characterized in that, It also includes a first diode and a first resistor, wherein the anode of the first diode is connected to the base of the transistor, and the first resistor is connected between the cathode of the first diode and the cathode of the Zener diode.

5. The overvoltage protection circuit according to claim 3, characterized in that, The third switching unit includes a MOS transistor, the gate of which is connected to the collector of the transistor, the source of which is grounded, and the drain of which is connected to the overvoltage protection port of the chip.

6. The overvoltage protection circuit according to claim 5, characterized in that, It also includes a second diode and a second resistor, the cathode of the second diode being connected to the gate of the MOS transistor, and the second resistor being connected between the anode of the second diode and the collector of the transistor.

7. The overvoltage protection circuit according to claim 6, characterized in that, It also includes a third resistor, one end of which is connected between the cathode of the second diode and the gate of the MOS transistor, and the other end of which is grounded.

8. The overvoltage protection circuit according to any one of claims 1 to 7, characterized in that, It also includes a sampling circuit, which is connected between the power supply and the first switching unit. The sampling circuit is used to sample the power supply voltage to obtain the sampled voltage.

9. The overvoltage protection circuit according to claim 8, characterized in that, The sampling circuit includes a fourth resistor, a fifth resistor, and a sixth resistor connected in series. The fourth resistor is connected to the power supply, the sixth resistor is grounded, and the first switching unit is connected between the fifth resistor and the sixth resistor.

10. An electrical device, characterized in that, Includes the overvoltage protection circuit as described in any one of claims 1 to 9.

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