A protection circuit and device

Abstract

The application belongs to the technical field of circuit and provides a protection circuit and equipment, the protection circuit comprises a first input end, a second input end, an output end, a first comparator, a second comparator, a third comparator, a first NOR gate, a second NOR gate, a first MOS tube, a second MOS tube and a NOT gate; the first input end is connected with the first MOS tube, the first comparator and the second comparator respectively, the first comparator and the first MOS tube are connected with the output end, the first comparator is further connected with the first NOR gate, and the first NOR gate is further connected with the first MOS tube; the second input end is connected with the second comparator, the second MOS tube and the third comparator respectively, the third comparator and the second MOS tube are connected with the output end, the third comparator is further connected with the second NOR gate, the second NOR gate is further connected with the second MOS tube, the second NOR gate and the second comparator are connected with the NOT gate, and the NOT gate is further connected with the first NOR gate. The application improves the reliability of voltage protection between circuits by combining the comparator with the NOT gate and the MOS tube.

Description

Technical Field

[0001] This invention belongs to the field of circuit technology, and in particular relates to a protection circuit and device. Background Technology

[0002] Circuits often experience high operational overvoltages when struck by lightning or when connecting or disconnecting inductive or large loads. These transient overvoltages are called surge voltages and are a type of transient interference. In real life, users inevitably connect the power cord incorrectly to electronic devices, or connect an incompatible power source. In other words, when the input voltage exceeds the device's nominal input voltage, it can damage the electronic components, causing malfunctions or even complete failure of the device.

[0003] Currently, existing protection circuits generally use diodes and MOSFETs to prevent reverse connection and reverse current. When the diodes and MOSFETs are subjected to instantaneous high voltage energy surges, they can quickly change their impedance to low impedance to absorb the instantaneous large current and protect the circuit.

[0004] However, the reliability of voltage protection between the various circuits in the above protection circuit is poor. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a protection circuit and device to solve the problem of poor reliability of voltage protection between circuits in the prior art.

[0006] A first aspect of the present invention provides a protection circuit, comprising:

[0007] First input terminal, second input terminal, output terminal, first comparator, second comparator, third comparator, first NOR gate, second NOR gate, first MOSFET, second MOSFET, NOT gate;

[0008] The first input terminal is connected to the source of the first MOS transistor, the first input terminal of the first comparator, and the second input terminal of the second comparator, respectively. The second input terminal of the first comparator and the drain of the first MOS transistor are both connected to the output terminal. The output terminal of the first comparator is connected to the first input terminal of the first NOR gate, and the output terminal of the first NOR gate is connected to the gate of the first MOS transistor.

[0009] The second input terminal is connected to the first input terminal of the second comparator, the source of the second MOS transistor, and the first input terminal of the third comparator, respectively. The second input terminal of the third comparator and the drain of the second MOS transistor are both connected to the output terminal. The output terminal of the third comparator is connected to the second input terminal of the second NOR gate. The output terminal of the second NOR gate is connected to the gate of the second MOS transistor. The first input terminal of the second NOR gate and the output terminal of the second comparator are both connected to the input terminal of the NOT gate. The output terminal of the NOT gate is connected to the second input terminal of the first NOR gate.

[0010] A second aspect of the present invention provides a protection circuit with voltage selection function, including the protection circuit described in the first aspect of the present invention.

[0011] A third aspect of the present invention provides a protection circuit with reverse connection protection function, including the protection circuit described in the first aspect of the present invention.

[0012] A fourth aspect of the present invention provides a protection circuit with anti-backflow function, including the protection circuit described in the first aspect of the present invention.

[0013] A fifth aspect of the present invention provides an apparatus including the protection circuit described in the first aspect of the present invention.

[0014] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows:

[0015] An embodiment of the present invention provides a protection circuit comprising: a first input terminal, a second input terminal, an output terminal, a first comparator, a second comparator, a third comparator, a first NOR gate, a second NOR gate, a first MOSFET, a second MOSFET, and a NOT gate; the first input terminal is connected to the source of the first MOSFET, the first input terminal of the first comparator, and the second input terminal of the second comparator; the second input terminal of the first comparator and the drain of the first MOSFET are both connected to the output terminal; the output terminal of the first comparator is connected to the first input terminal of the first NOR gate; the output terminal of the first NOR gate is connected to the gate of the first MOSFET; the second input terminal is connected to the first input terminal of the second comparator, the source of the second MOSFET, and the first input terminal of the third comparator; the second input terminal of the third comparator and the drain of the second MOSFET are both connected to the output terminal; the output terminal of the third comparator is connected to the second input terminal of the second NOR gate; the output terminal of the second NOR gate is connected to the gate of the second MOSFET; the first input terminal of the second NOR gate and the output terminal of the second comparator are both connected to the input terminal of the NOT gate; the output terminal of the NOT gate is connected to the second input terminal of the first NOR gate. This invention effectively improves the reliability of voltage protection between different circuits in the protection circuit by combining comparators, NAND gates, and MOSFETs. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a protection circuit provided in an embodiment of the present invention. Detailed Implementation

[0018] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0019] To illustrate the technical solution described in this invention, specific embodiments are described below.

[0020] Figure 1 This is a schematic diagram of a protection circuit provided in an embodiment of the present invention. Figure 1 As shown, one embodiment of the protection circuit includes:

[0021] First input terminal Vin1, second input terminal Vin2, output terminal Vout, first comparator (comparator 1), second comparator (comparator 2), third comparator (comparator 3), first NOR gate (NOR gate 1), second NOR gate (NOR gate 2), first MOSFET (MOSFET 1), second MOSFET (MOSFET 2), and NOT gate;

[0022] The first input terminal Vin1 is connected to the source S of the first MOS transistor, the first input terminal 1 of the first comparator, and the second input terminal 2 of the second comparator. The second input terminal 2 of the first comparator and the drain D of the first MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the first comparator is connected to the first input terminal 1 of the first NOR gate, and the output terminal 3 of the first NOR gate is connected to the gate G of the first MOS transistor.

[0023] The second input terminal Vin2 is connected to the first input terminal 1 of the second comparator, the source S of the second MOS transistor, and the first input terminal 1 of the third comparator. The second input terminal 2 of the third comparator and the drain D of the second MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the third comparator is connected to the second input terminal 2 of the second NOR gate. The output terminal 3 of the second NOR gate is connected to the gate G of the second MOS transistor. The first input terminal 1 of the second NOR gate and the output terminal 3 of the second comparator are both connected to the input terminal of the NOT gate. The output terminal of the NOT gate is connected to the second input terminal 2 of the first NOR gate.

[0024] In one embodiment, the first comparator, the second comparator, and the third comparator may be voltage comparators.

[0025] In one embodiment, the voltage comparator includes: a single-limit comparator, a hysteresis comparator, a window comparator, and a three-state voltage comparator.

[0026] Specifically, taking an example where the first, second, and third comparators are all single-limit comparators—that is, the first comparator is a first-limit comparator, the second comparator is a second-limit comparator, and the third comparator is a third-limit comparator—as combined with... Figure 1The protection circuit of this application includes: a first input terminal Vin1, a second input terminal Vin2, an output terminal Vout, a first single-threshold comparator (comparator 1), a second single-threshold comparator (comparator 2), a third single-threshold comparator (comparator 3), a first NOR gate (NOR gate 1), a second NOR gate (NOR gate 2), a first MOSFET (MOSFET 1), a second MOSFET (MOSFET 2), and a NOT gate; the first input terminal Vin1 is connected to the source S of the first MOSFET, the first input terminal 1 of the first single-threshold comparator, and the second input terminal 2 of the second single-threshold comparator, respectively; the second input terminal 2 of the first single-threshold comparator and the drain D of the first MOSFET are both connected to the output terminal Vout; the output terminal 3 of the first single-threshold comparator is connected to the first NOR gate (NOR gate 1), the second NOR gate (NOR gate 2), the third NOR gate (NOR gate 3), and the fourth NOR gate (NOR gate 3). The first input terminal 1 of the gate and the output terminal 3 of the first NOR gate are connected to the gate G of the first MOS transistor. The second input terminal Vin2 is connected to the first input terminal 1 of the second single-threshold comparator, the source S of the second MOS transistor, and the first input terminal 1 of the third single-threshold comparator. The second input terminal 2 of the third single-threshold comparator and the drain D of the second MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the third single-threshold comparator is connected to the second input terminal 2 of the second NOR gate. The output terminal 3 of the second NOR gate is connected to the gate G of the second MOS transistor. The first input terminal 1 of the second NOR gate and the output terminal 3 of the second single-threshold comparator are both connected to the input terminal of the NOT gate. The output terminal of the NOT gate is connected to the second input terminal 2 of the first NOR gate.

[0027] Combination Figure 1 A schematic diagram of a protection circuit with voltage selection function is provided in one embodiment of the present invention. This protection circuit with voltage selection function includes:

[0028] First input terminal Vin1, second input terminal Vin2, output terminal Vout, first comparator (comparator 1), second comparator (comparator 2), third comparator (comparator 3), first NOR gate (NOR gate 1), second NOR gate (NOR gate 2), first MOSFET (MOSFET 1), second MOSFET (MOSFET 2), and NOT gate;

[0029] The first input terminal Vin1 is connected to the source S of the first MOS transistor, the first input terminal 1 of the first comparator, and the second input terminal 2 of the second comparator. The second input terminal 2 of the first comparator and the drain D of the first MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the first comparator is connected to the first input terminal 1 of the first NOR gate, and the output terminal 3 of the first NOR gate is connected to the gate G of the first MOS transistor.

[0030] The second input terminal Vin2 is connected to the first input terminal 1 of the second comparator, the source S of the second MOS transistor, and the first input terminal 1 of the third comparator. The second input terminal 2 of the third comparator and the drain D of the second MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the third comparator is connected to the second input terminal 2 of the second NOR gate. The output terminal 3 of the second NOR gate is connected to the gate G of the second MOS transistor. The first input terminal 1 of the second NOR gate and the output terminal 3 of the second comparator are both connected to the input terminal of the NOT gate. The output terminal of the NOT gate is connected to the second input terminal 2 of the first NOR gate.

[0031] In one embodiment, the first comparator, the second comparator, and the third comparator may be voltage comparators.

[0032] In one embodiment, the voltage comparator includes: a single-limit comparator, a hysteresis comparator, a window comparator, and a three-state voltage comparator.

[0033] In one embodiment, when the input voltage of the first input terminal Vin1 is greater than the input voltage of the second input terminal Vin2, the second comparator outputs a low level, which is then passed through the NOT gate to output a high level. The first comparator outputs a high level, and the high level output by the first comparator and the low level are passed through the NOT gate to output a high level, which is then passed through the first NOR gate to output a low level. The first MOSFET is turned on. The third comparator outputs a high level, which is then passed through the second NOR gate to output a high level. The second MOSFET is turned off, and the output voltage of the output terminal Vout is equal to the input voltage of the first input terminal Vin1.

[0034] When the input voltage at the first input terminal Vin1 is less than the input voltage at the second input terminal Vin2, the second comparator outputs a high level. The high level output by the second comparator is then passed through the NOT gate to output a low level. The first comparator outputs a high level. The high level output by the first comparator and the low level output by the high level are passed through the NOT gate to output a high level. The first MOSFET is turned off. The third comparator outputs a high level. The high level output by the third comparator and the high level output by the second comparator are then passed through the second NOR gate to output a low level. The second MOSFET is turned on. The output voltage at the output terminal Vout is equal to the input voltage at the second input terminal Vin2.

[0035] When voltages are simultaneously input to the first and second input terminals, a higher output voltage is achieved. The output voltage can be selected by replacing the input stage of the second comparator, or by adding more comparators to select more voltage channels.

[0036] Combination Figure 1 A schematic diagram of a protection circuit with reverse connection protection function is provided in one embodiment of the present invention. This protection circuit with reverse connection protection function includes:

[0037] First input terminal Vin1, second input terminal Vin2, output terminal Vout, first comparator (comparator 1), second comparator (comparator 2), third comparator (comparator 3), first NOR gate (NOR gate 1), second NOR gate (NOR gate 2), first MOSFET (MOSFET 1), second MOSFET (MOSFET 2), and NOT gate;

[0038] The first input terminal Vin1 is connected to the source S of the first MOS transistor, the first input terminal 1 of the first comparator, and the second input terminal 2 of the second comparator. The second input terminal 2 of the first comparator and the drain D of the first MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the first comparator is connected to the first input terminal 1 of the first NOR gate, and the output terminal 3 of the first NOR gate is connected to the gate G of the first MOS transistor.

[0039] The second input terminal Vin2 is connected to the first input terminal 1 of the second comparator, the source S of the second MOS transistor, and the first input terminal 1 of the third comparator. The second input terminal 2 of the third comparator and the drain D of the second MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the third comparator is connected to the second input terminal 2 of the second NOR gate. The output terminal 3 of the second NOR gate is connected to the gate G of the second MOS transistor. The first input terminal 1 of the second NOR gate and the output terminal 3 of the second comparator are both connected to the input terminal of the NOT gate. The output terminal of the NOT gate is connected to the second input terminal 2 of the first NOR gate.

[0040] In one embodiment, the first comparator, the second comparator, and the third comparator may be voltage comparators.

[0041] In one embodiment, the voltage comparator includes: a single-limit comparator, a hysteresis comparator, a window comparator, and a three-state voltage comparator.

[0042] In one embodiment, when the first input terminal Vin1 is reversed, the first comparator outputs a low level, the low level is passed through the first NOR gate to output a high level, the first MOSFET is turned off, the second comparator outputs a low level, the low level output by the second comparator is passed through the second NOR gate to output a high level, the second MOSFET is turned off, and the output terminal has no output voltage.

[0043] When the second input terminal Vin2 is reversed, the third comparator outputs a low level. The low level output by the third comparator is passed through the second NOR gate and then outputs a high level. The second MOSFET is turned off. The second comparator outputs a low level. The low level output by the second comparator is passed through the NOT gate and then outputs a high level. The high level output by the NOT gate is passed through the first NOR gate and then outputs a high level. The first MOSFET is turned off.

[0044] Combination Figure 1 A schematic diagram of a protection circuit with anti-backflow function is provided in one embodiment of the present invention. This protection circuit with anti-backflow function includes:

[0045] First input terminal Vin1, second input terminal Vin2, output terminal Vout, first comparator (comparator 1), second comparator (comparator 2), third comparator (comparator 3), first NOR gate (NOR gate 1), second NOR gate (NOR gate 2), first MOSFET (MOSFET 1), second MOSFET (MOSFET 2), and NOT gate;

[0046] The first input terminal Vin1 is connected to the source S of the first MOS transistor, the first input terminal 1 of the first comparator, and the second input terminal 2 of the second comparator. The second input terminal 2 of the first comparator and the drain D of the first MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the first comparator is connected to the first input terminal 1 of the first NOR gate, and the output terminal 3 of the first NOR gate is connected to the gate G of the first MOS transistor.

[0047] The second input terminal Vin2 is connected to the first input terminal 1 of the second comparator, the source S of the second MOS transistor, and the first input terminal 1 of the third comparator. The second input terminal 2 of the third comparator and the drain D of the second MOS transistor are both connected to the output terminal Vout. The output terminal 3 of the third comparator is connected to the second input terminal 2 of the second NOR gate. The output terminal 3 of the second NOR gate is connected to the gate G of the second MOS transistor. The first input terminal 1 of the second NOR gate and the output terminal 3 of the second comparator are both connected to the input terminal of the NOT gate. The output terminal of the NOT gate is connected to the second input terminal 2 of the first NOR gate.

[0048] In one embodiment, the first comparator, the second comparator, and the third comparator may be voltage comparators.

[0049] In one embodiment, the voltage comparator includes: a single-limit comparator, a hysteresis comparator, a window comparator, and a three-state voltage comparator.

[0050] In one embodiment, when the voltage at the output terminal Vout is greater than the voltage at the first input terminal Vin1, the first comparator outputs a low level, and the low level is output as a high level after passing through the first NOR gate, and the first MOS transistor is turned off.

[0051] When the voltage at the output terminal Vout is greater than the voltage at the second input terminal Vin2, the third comparator outputs a low level. This low level output is then passed through the second NOR gate to output a high level, and the second MOSFET is turned off. The protection circuit in the above embodiment can prevent reverse current flow and damage to the front-end circuit. Furthermore, the circuit used in this application is low-cost, has a fast protection activation time, and exhibits a very small voltage difference between the output and input.

[0052] An embodiment of the present invention also provides a device, the device including any of the protection circuits described above.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A protection circuit, characterized in that, include: First input terminal, second input terminal, output terminal, first comparator, second comparator, third comparator, first NOR gate, second NOR gate, first MOSFET, second MOSFET, NOT gate; The first input terminal is connected to the source of the first MOS transistor, the first input terminal of the first comparator, and the second input terminal of the second comparator, respectively. The second input terminal of the first comparator and the drain of the first MOS transistor are both connected to the output terminal. The output terminal of the first comparator is connected to the first input terminal of the first NOR gate, and the output terminal of the first NOR gate is connected to the gate of the first MOS transistor. The second input terminal is connected to the first input terminal of the second comparator, the source of the second MOS transistor, and the first input terminal of the third comparator, respectively. The second input terminal of the third comparator and the drain of the second MOS transistor are both connected to the output terminal. The output terminal of the third comparator is connected to the second input terminal of the second NOR gate. The output terminal of the second NOR gate is connected to the gate of the second MOS transistor. The first input terminal of the second NOR gate and the output terminal of the second comparator are both connected to the input terminal of the NOT gate. The output terminal of the NOT gate is connected to the second input terminal of the first NOR gate.

2. The protection circuit as described in claim 1, characterized in that, The first comparator, the second comparator, and the third comparator are voltage comparators.

3. The protection circuit as described in claim 2, characterized in that, The voltage comparator includes: a single-limit comparator, a hysteresis comparator, a window comparator, and a three-state voltage comparator.

4. The protection circuit as described in claim 1, characterized in that, When the input voltage at the first input terminal is greater than the input voltage at the second input terminal, the second comparator outputs a low level. This low level is then passed through the NOT gate to output a high level. The first comparator outputs a high level. The high level output by the first comparator and the low level output are passed through the NOT gate to output a high level. This high level output is then passed through the first NOR gate to output a low level, and the first MOSFET is turned on. The third comparator outputs a high level. The high level output by the third comparator and the low level output by the second comparator are passed through the second NOR gate to output a high level, and the second MOSFET is turned off. The output voltage at the output terminal is equal to the input voltage at the first input terminal. When the input voltage at the first input terminal is less than the input voltage at the second input terminal, the second comparator outputs a high level. The high level output by the second comparator is passed through the NOT gate and outputs a low level. The first comparator outputs a high level. The high level output by the first comparator and the low level output by the high level are passed through the NOT gate and output a high level through the first NOR gate. The first MOSFET is turned off. The third comparator outputs a high level. The high level output by the third comparator and the high level output by the second comparator are passed through the second NOR gate and output a low level. The second MOSFET is turned on. The output voltage at the output terminal is equal to the input voltage at the second input terminal.

5. A device, characterized in that, Includes the protection circuit described in any one of claims 1-3.

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