Overvoltage protection and sensing circuit and analog input detection device

Abstract

The utility model discloses an overvoltage protection and sensing circuit and an analog input detection device. Relates to the technical field of analog quantity detection. According to the scheme, on the basis of a traditional analog quantity input detection technology, the structure is improved; the self-recovery fuse F1 and the transient suppression diode TVS1 are utilized to generate voltage difference at two ends of the self-recovery fuse during overvoltage, and the PMOS tube Q1 is switched on when negative voltage is generated at two ends of the G pole and the S pole by utilizing the conduction characteristic of the PMOS tube Q1. The two are ingeniously combined, that is, the voltage difference generated at the two ends of the resettable fuse is applied to the G pole and the S pole of the PMOS tube Q1 to sense overvoltage; therefore, the purposes of simplifying devices and saving material cost are achieved, the current consumption of analog signals is reduced, the sensing circuit almost has no leakage current in a normal state, and the influence on the signals is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to analog quantity detection technical field, concretely relates to a kind of overvoltage protection and sensing circuit and analog quantity input detection device. BACKGROUND

[0002] Analog quantity input detection circuit is important circuit of industrial automation equipment, is widely applied in voltage signal or current detection. Voltage signal or current signal voltage amplitude is very weak, and there are many power supply connecting wires in actual factory, in installation process detection equipment process or use process, power line can be connected to analog quantity input module terminal, if there is no overvoltage and overcurrent protection, subsequent circuit will be burned, therefore, overvoltage or overcurrent protection to signal is very necessary. At the same time, when high voltage is connected to analog input circuit, but at this time, there is protection circuit, if there is no prompt, long time can cause protection circuit failure, cause more serious problem, therefore, it is necessary to increase the prompt of overvoltage protection. For maintenance, quickly recover and solve overvoltage fault point. INVENTION CONTENTS

[0003] The utility model solves the technical problems that: traditional analog quantity input detection circuit does not consider overvoltage and overcurrent protection, is easy to cause circuit burn in the process of detecting analog quantity;The utility model aims at providing a kind of overvoltage protection and sensing circuit and analog quantity input detection device, on the basis of traditional analog quantity input detection technology, structural improvement is carried out;Using self-restoring fuse F1 and transient voltage suppression diode TVS1, so that voltage difference is generated at the two ends of self-restoring fuse when overvoltage, and using the conduction characteristic of PMOS tube Q1, PMOS tube Q1 is turned on when negative voltage is generated at the two ends of G pole and S pole. The two are ingeniously combined, that is, the voltage difference generated at the two ends of self-restoring fuse is applied to the G pole and S pole of PMOS tube Q1, and overvoltage is sensed. Thus, the purpose of simplifying devices and saving material cost is achieved, current consumption of analog signal is reduced, sensing circuit has almost no leakage current in normal state, and the influence on signal is reduced.

[0004] The utility model realizes by following technical scheme:

[0005] The present application provides an overvoltage protection and sensing circuit, comprising:

[0006] An overvoltage sensing unit is used to sense whether the analog signal is overvoltage. The overvoltage sensing unit is connected to the analog signal input end.

[0007] An overvoltage protection unit is used to perform protection action when the analog signal is overvoltage. The overvoltage protection unit is electrically connected to the overvoltage sensing unit.

[0008] An output conversion unit is used to perform level conversion on the analog signal. The output conversion unit is electrically connected to the overvoltage sensing unit.

[0009] The working principle of the scheme is: the traditional analog quantity input detection circuit does not consider overvoltage and overcurrent protection, which is easy to cause the circuit to burn out in the process of detecting analog quantity; the utility model discloses an overvoltage protection and sensing circuit and analog quantity input detection device, which is improved in structure on the basis of traditional analog quantity input detection technology; by using self-resetting fuse F1 and transient voltage suppression diode TVS1, a voltage difference is generated at both ends of the self-resetting fuse when overvoltage occurs, and by using the conduction characteristic of PMOS tube Q1, the PMOS tube Q1 is turned on when a negative voltage is generated at both ends of the G pole and the S pole. The two are ingeniously combined, that is, the voltage difference generated at both ends of the self-resetting fuse is applied to the G pole and the S pole of the PMOS tube Q1 to sense overvoltage. Thus, the purpose of saving materials and reducing current consumption of analog signals is achieved, and the sensing circuit has almost no leakage current in normal state, reducing the influence on signals.

[0010] The further optimization scheme is that the overvoltage sensing unit comprises a resistor R1, a resistor R5, a MOS tube Q1 and a voltage stabilizing tube D1.

[0011] One end of the resistor R5 is connected to the analog signal input end, and the other end is connected to the overvoltage protection unit after being connected in series with the resistor R1. The positive electrode of the voltage stabilizing tube D1 is connected between the resistor R1 and the resistor R5, and the negative electrode of the voltage stabilizing tube D1 is connected to the analog signal input end.

[0012] The G pole of the MOS tube Q1 is connected between the resistor R1 and the resistor R5, the S pole of the MOS tube Q1 is connected to the analog signal input end, and the D pole of the MOS tube Q1 is connected to the output conversion unit.

[0013] The further optimization scheme is that the overvoltage protection unit comprises a transient voltage suppression diode TVS1, a transient voltage suppression diode TVS2 and a self-resetting fuse F1.

[0014] One end of the transient voltage suppression diode TVS1 is connected to the analog signal input end, and the other end is grounded. The first end of the self-resetting fuse F1 is connected to the analog signal input end, and the second end of the self-resetting fuse F1 is connected to the resistor R1. One end of the transient voltage suppression diode TVS2 is connected to the second end of the self-resetting fuse F1, and the other end is grounded.

[0015] The further optimization scheme is that the output conversion unit comprises a resistor R3, a resistor R4, a voltage stabilizing tube D2, a MOS tube Q2, a resistor R6, a resistor R2 and a light-emitting diode LED1.

[0016] One end of the resistor R3 is connected to the D pole of the P-type MOS tube Q1, and the other end is connected to the G pole of the MOS tube Q2; the positive pole of the stabilizing tube D2 is grounded, and the negative pole of the stabilizing tube D2 is connected to the D pole of the MOS tube Q2; the S pole of the MOS tube Q2 is grounded, and the D pole of the MOS tube Q2 is connected to the VCC power supply after being connected with the resistor R2 in series; the positive pole of the light emitting diode LED1 is connected to the VCC power supply, and the negative pole of the light emitting diode LED1 is connected to the D pole of the MOS tube Q2 after being connected with the resistor R6 in series, and the D pole of the MOS tube Q2 is used as an output end.

[0017] Further optimization scheme is that the MOS tube Q2 is an N-type MOS tube, and the MOS tube Q1 is a P-type MOS tube.

[0018] Further optimization scheme is that the circuit further comprises a clamping unit for clamping an analog signal voltage; and the clamping unit is electrically connected with the overvoltage protection unit.

[0019] Further optimization scheme is that the clamping unit comprises a resistor R7, a first diode and a second diode.

[0020] The negative pole of the first diode is connected to the positive pole of the second diode, the positive pole of the first diode is connected to the positive VCC power supply, and the negative pole of the second diode is connected to the negative VCC power supply.

[0021] One end of the resistor R7 is connected to the second end of the self-recovery fuse F1, and the other end is connected to the negative pole of the first diode.

[0022] Further optimization scheme is that the clamping unit clamps the analog signal voltage to between (-VCC, VCC).

[0023] Further optimization scheme is that the clamping voltage of the transient voltage suppression diode TVS1 is U1, the clamping voltage of the transient voltage suppression diode TVS2 is U2, the maximum voltage allowed by the circuit is Umax, and the working voltage is Uop.

[0024] Requirements are Umax>U1>Uop, and U2>>U1, U2≥Upowermax; Upowermax is the maximum value of the power supply.

[0025] The scheme also provides an over-analog input detection device, which comprises the overvoltage protection and sensing circuit.

[0026] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0027] The utility model provides a kind of overvoltage protection and sensing circuit and analog quantity input detection device, the scheme is improved on structure based on traditional analog quantity input detection technology;Utilize self-restoring fuse F1 and transient voltage suppressor TVS1, so that voltage difference is generated at the both ends of self-restoring fuse when overvoltage, and using the conduction characteristic of PMOS tube Q1, when negative voltage is generated at the both ends of G pole and S pole, PMOS tube Q1 is turned on.Cleverly combine the two, i.e. the voltage difference generated at the both ends of self-restoring fuse is applied to the G pole and S pole of PMOS tube Q1, and overvoltage is sensed;So as to achieve the purpose of saving material cost by simplifying device, reduce the current consumption of analog signal, and reduce the influence on signal under normal state sensing circuit almost no leakage current. BRIEF DESCRIPTION OF DRAWINGS

[0028] The drawings described herein are used to provide further understanding of the embodiments of the utility model, constitute a part of this application, and do not constitute the limitation to the embodiments of the utility model.In the drawings:

[0029] Figure 1 It is overvoltage protection and sensing circuit structure schematic diagram;

[0030] Figure 2 It is overvoltage protection and sensing circuit schematic diagram. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantage of the utility model more clear and obvious, the utility model is further explained in detail in the following combining with embodiment and drawing, and the illustrative embodiment of the utility model and its explanation are only used to explain the utility model, and not as the limitation to the utility model.

[0032] The analog quantity input detection circuit is an important circuit of industrial automation equipment, and is widely used in voltage signal or current detection.The voltage amplitude of voltage signal or current signal is very weak, and there are many power supply connection lines in actual factory, and during installation process, detection equipment process or use process, power supply line can be connected to the terminal of analog quantity input module, and if there is no overvoltage and overcurrent protection, subsequent circuit can be burned, so it is necessary to protect signal from overvoltage or overcurrent protection.At the same time, when high voltage is connected to analog input circuit, but there is protection circuit at this time, if there is no prompt, long time can cause protection circuit failure, cause more serious problem, so it is necessary to increase the prompt of overvoltage protection.For fast recovery and solve overvoltage fault point when maintaining.

[0033] Therefore, the scheme provides the following embodiments to solve the above technical problems:

[0034] Embodiment 1

[0035] The embodiment provides an overvoltage protection and sensing circuit, as Figure 1and Figure 2 illustrated, comprising:

[0036] an overvoltage sensing unit for sensing whether the analog signal is overvoltage; the overvoltage sensing unit is connected to the analog signal input end;

[0037] an overvoltage protection unit for protection action when the analog signal is overvoltage; the overvoltage protection unit is electrically connected with the overvoltage sensing unit;

[0038] an output conversion unit for level conversion of the analog signal; the output conversion unit is electrically connected with the overvoltage sensing unit.

[0039] The overvoltage sensing unit comprises: a resistor R1, a resistor R5, a MOS tube Q1, and a voltage stabilizing tube D1.

[0040] One end of the resistor R5 is connected to the analog signal input end, and the other end is connected to the overvoltage protection unit after being connected in series with the resistor R1; the positive electrode of the voltage stabilizing tube D1 is connected between the resistor R1 and the resistor R5, and the negative electrode of the voltage stabilizing tube D1 is connected to the analog signal input end.

[0041] The G pole of the MOS tube Q1 is connected between the resistor R1 and the resistor R5, the S pole of the MOS tube Q1 is connected to the analog signal input end, and the D pole of the MOS tube Q1 is connected to the output conversion unit.

[0042] The overvoltage protection unit comprises: a transient voltage suppression diode TVS1, a transient voltage suppression diode TVS2, and a self-resetting fuse F1.

[0043] One end of the transient voltage suppression diode TVS1 is connected to the analog signal input end, and the other end is grounded; the first end of the self-resetting fuse F1 is connected to the analog signal input end, the second end of the self-resetting fuse F1 is connected to the resistor R1; one end of the transient voltage suppression diode TVS2 is connected to the second end of the self-resetting fuse F1, and the other end is grounded.

[0044] The output conversion unit comprises: a resistor R3, a resistor R4, a voltage stabilizing tube D2, a MOS tube Q2, a resistor R6, a resistor R2, and a light-emitting diode LED1.

[0045] One end of the resistor R3 is connected to the D pole of the P-type MOS tube Q1, and the other end is connected to the G pole of the MOS tube Q2; the positive electrode of the voltage stabilizing tube D2 is grounded, and the negative electrode of the voltage stabilizing tube D2 is connected to the D pole of the MOS tube Q2; the S pole of the MOS tube Q2 is grounded, and the D pole of the MOS tube Q2 is connected to the VCC power supply after being connected in series with the resistor R2; the positive electrode of the light-emitting diode LED1 is connected to the VCC power supply, the negative electrode of the light-emitting diode LED1 is connected to the D pole of the MOS tube Q2 after being connected in series with the resistor R6, and the D pole of the MOS tube Q2 serves as the output end.

[0046] The MOS tube Q2 is an N-type MOS tube, and the MOS tube Q1 is a P-type MOS tube.

[0047] The clamping unit is also used for clamping the analog signal voltage; the clamping unit is electrically connected with the overvoltage protection unit.

[0048] The clamping unit comprises a resistor R7, a first diode and a second diode.

[0049] The negative pole of the first diode is connected with the positive pole of the second diode, the positive pole of the first diode is connected with the positive VCC power supply, and the negative pole of the second diode is connected with the negative VCC power supply.

[0050] One end of the resistor R7 is connected with the second end of the self-recovery fuse F1, and the other end is connected with the negative pole of the first diode.

[0051] The clamping unit clamps the analog signal voltage between (-VCC, VCC).

[0052] The clamping voltage of the transient voltage suppression diode TVS1 is U1, the clamping voltage of the transient voltage suppression diode TVS2 is U2, the maximum voltage allowed by the circuit is Umax, and the working voltage is Uop.

[0053] It is required that Umax> U1> Uop, and U2>> U1, U2≥Upowermax; Upowermax is the maximum value of the power supply.

[0054] Figure 2 The AIN signal is an analog input signal, the clamping voltage of the transient voltage suppression diode TVS1 is U1, the clamping voltage of the transient voltage suppression diode TVS2 is U2, the maximum voltage allowed by the circuit is Umax, and the working voltage is Uop. At this time, it is required that Umax> U1> Uop, and U2 is much greater than U1. If the maximum power supply in the field is Upowermax, then U2≥Upowermax.

[0055] The maximum working current IF of the self-recovery fuse F1 should meet the analog input sampling requirements, and the maximum working current IF is as small as possible.

[0056] The voltage stabilizing tube D1 is used for protecting the G pole and the S pole of the MOS tube Q1 from exceeding the maximum allowed voltage, and the voltage stabilizing tube D2 is used for protecting the G pole and the S pole of the MOS tube Q2 from exceeding the maximum allowed voltage.

[0057] The first diode and the second diode clamp the analog voltage signal between (-VCC, VCC); when AIN accesses the high-voltage power supply Vpower, due to the clamping effect of the transient voltage suppression diode TVS1, the voltage at the back end of the self-restoring fuse F1 is kept at the clamping voltage of the transient voltage suppression diode TVS1, so that the voltage between the self-restoring fuse F1 is kept at Vpower-U1, and then a voltage difference exists on the path in series connection of the resistor R5 and the resistor R1, if the voltage across the resistor R5 is greater than the opening voltage of the G pole and the S pole of the MOS tube Q1, then the MOS tube Q1 is turned on, so that the high-voltage power supply passes through the MOS tube Q1, is divided by the resistor R3 and the resistor R4, and then a voltage difference is formed at the G pole and the S pole of the MOS tube Q2, so that the MOS tube Q2 is turned on, and then the drain of the MOS tube Q2 is pulled low, the level state is reversed, and the LED1 is lighted, and the level signal can be obtained by the GPIO of the MCU, so that the generation of the overvoltage fault is sensed. Meanwhile, the LED1 can be arranged at the analog detection port and used for prompting the overvoltage fault position.

[0058] When AIN is in the normal working state, the working voltage Vop is less than U1 at this time, the transient voltage suppression diode TVS1 does not work, there is no voltage difference across the self-restoring fuse F1, there is no voltage at the G pole and the S pole of the MOS tube Q1, the MOS tube Q1 cannot be opened, the back-end MOS tube Q2 is not turned on, the drain of the MOS tube Q2 maintains the high-level state, and the LED1 is not lighted.

[0059] The scheme utilizes the self-restoring fuse F1 and the transient voltage suppression diode TVS1 to make the voltage difference generated across the self-restoring fuse in the overvoltage state, and utilizes the PMOS tube Q1 conduction characteristic, so that the PMOS tube Q1 is turned on when the negative voltage is generated across the G pole and the S pole. The two are ingeniously combined, that is, the voltage difference generated across the self-restoring fuse is applied to the G pole and the S pole of the PMOS tube Q1 to sense the overvoltage. Thus, the purpose of simplifying devices and saving material costs is achieved, the current consumption of the analog signal is reduced, the sensing circuit almost has no leakage current in the normal state, and the influence on the signal is reduced.

[0060] Embodiment 2

[0061] The embodiment provides an over-analog quantity input detection device, which comprises the overvoltage protection and sensing circuit in the embodiment 1.

[0062] The above specific embodiments further specifically describe the purpose, technical scheme and beneficial effects of the utility model, and it should be understood that the above description is only a specific embodiment of the utility model and is not used to limit the protection scope of the utility model, and any modification, equivalent replacement, improvement and the like made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. An overvoltage protection and sensing circuit, comprising: The application relates to an overvoltage protection circuit for an analog signal input terminal. The overvoltage protection circuit comprises an overvoltage sensing unit, an overvoltage protection unit and an output conversion unit. The overvoltage sensing unit is connected to the analog signal input terminal. The overvoltage sensing unit comprises a resistor R1, a resistor R5, a MOS tube Q1 and a voltage stabilizing tube D1. One end of the resistor R5 is connected to the analog signal input terminal, and the other end is connected to the overvoltage protection unit after being connected in series with the resistor R1. The positive electrode of the voltage stabilizing tube D1 is connected between the resistor R1 and the resistor R5, and the negative electrode of the voltage stabilizing tube D1 is connected to the analog signal input terminal. The G electrode of the MOS tube Q1 is connected between the resistor R1 and the resistor R5, the S electrode of the MOS tube Q1 is connected to the analog signal input terminal, and the D electrode of the MOS tube Q1 is connected to the output conversion unit. The overvoltage protection unit is used for protection when the analog signal is overvoltage. The overvoltage protection unit is electrically connected to the overvoltage sensing unit. The overvoltage protection unit comprises a transient voltage suppression diode TVS1, a transient voltage suppression diode TVS2 and a self-recovery fuse F1.

2. An overvoltage protection and sensing circuit according to claim 1, wherein, One end of the transient voltage suppression diode TVS1 is connected to the analog signal input terminal, and the other end is grounded.

3. An overvoltage protection and sensing circuit according to claim 1, wherein, The first end of the self-recovery fuse F1 is connected to the analog signal input terminal, and the second end of the self-recovery fuse F1 is connected to the resistor R1.

4. An overvoltage protection and sensing circuit according to claim 3, wherein, One end of the transient voltage suppression diode TVS2 is connected to the second end of the self-recovery fuse F1, and the other end is grounded. The output conversion unit is used for level conversion of the analog signal. The output conversion unit is electrically connected to the overvoltage sensing unit.

5. An overvoltage protection and sensing circuit according to claim 4, wherein, The output conversion unit comprises a resistor R3, a resistor R4, a voltage stabilizing tube D2, a MOS tube Q2, a resistor R6, a resistor R2 and a light emitting diode LED1.

6. An overvoltage protection and sensing circuit according to claim 1, wherein, One end of the resistor R3 is connected to the D electrode of the P-type MOS tube Q1, and the other end is connected to the G electrode of the MOS tube Q2. The positive electrode of the voltage stabilizing tube D2 is grounded, and the negative electrode of the voltage stabilizing tube D2 is connected to the D electrode of the MOS tube Q2. The S electrode of the MOS tube Q2 is grounded, the D electrode of the MOS tube Q2 is connected to a VCC power source after being connected in series with the resistor R2, the positive electrode of the light emitting diode LED1 is connected to the VCC power source, the negative electrode of the light emitting diode LED1 is connected to the D electrode of the MOS tube Q2 after being connected in series with the resistor R6, and the D electrode of the MOS tube Q2 is used as an output terminal. The MOS tube Q2 is an N-type MOS tube, and the MOS tube Q1 is a P-type MOS tube. The overvoltage protection circuit further comprises a clamping unit used for clamping the voltage of the analog signal. The clamping unit is electrically connected to the overvoltage protection unit. The clamping unit comprises a resistor R7, a first diode and a second diode. The negative electrode of the first diode is connected to the positive electrode of the second diode, the positive electrode of the first diode is connected to a positive VCC power source, and the negative electrode of the second diode is connected to a negative VCC power source. One end of the resistor R7 is connected to the second end of the self-recovery fuse F1, and the other end is connected to the negative electrode of the first diode. The clamping unit clamps the voltage of the analog signal to (-VCC, VCC). The clamping voltage of the transient voltage suppression diode TVS1 is U1, the clamping voltage of the transient voltage suppression diode TVS2 is U2, the maximum voltage allowed by the circuit is Umax, and the working voltage is Uop. It is required that Umax>U1>Uop, U2>>U1, and U2>=Upowermax. Upowermax is the maximum value of the power supply.

7. An analog input detection device, characterized by An overvoltage protection and sensing circuit comprising any one of claims 1-6.

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