CN115980432A

CN115980432A - Voltage detection circuit

Info

Publication number: CN115980432A
Application number: CN202211714633.XA
Authority: CN
Inventors: 王冠君; 谢亚运; 朱良; 陆超; 孔斌; 冯维星
Original assignee: SHANGHAI HIGH GAIN INFORMATION TECHNOLOGY CO LTD
Current assignee: SHANGHAI HIGH GAIN INFORMATION TECHNOLOGY CO LTD
Priority date: 2022-12-29
Filing date: 2022-12-29
Publication date: 2023-04-18

Abstract

A voltage detection circuit is applied to the technical field of electronics. The circuit includes a low voltage processing circuit and a high voltage processing circuit coupled to the low voltage processing circuit. The input end of the low-voltage processing circuit is connected with a power supply, and the output end of the high-voltage processing circuit is connected with a load; the low-voltage processing circuit is used for limiting the input voltage to flow into the high-voltage processing circuit when the input voltage of the power supply is lower than a low-voltage threshold value; the high-voltage processing circuit is used for reducing the input voltage when the input voltage of the power supply is higher than a high-voltage threshold value, and outputting the reduced input voltage to a load. According to the scheme, when the input voltage of the power supply is lower than the low-voltage threshold value, the load can be in a rest state; in addition, when the input voltage of the power supply is higher than the low-voltage threshold value and lower than the high-voltage threshold value, the load is enabled to be in the working state. Because the low-voltage processing circuit and the high-voltage processing circuit have lower capital cost and high response speed, the scheme can realize the control of the voltage with low capital cost and high response speed.

Description

Voltage detection circuit

Technical Field

The invention relates to the technical field of electronics, in particular to a voltage detection circuit.

Background

The voltage detection circuit is used for controlling the working state of the circuit system. When the voltage value of the input voltage received by the voltage detection circuit is within the working voltage range of the circuit system, the voltage detection circuit outputs the working voltage to the circuit system, so that the load in the circuit system works normally. When the voltage value of the input voltage received by the voltage detection circuit does not belong to the working voltage range of the circuit system, the voltage detection circuit does not output voltage to the circuit system, or the voltage detection circuit outputs 0V voltage to the circuit system, so that a load in the circuit system does not work.

At present, the voltage detection circuit generally consists of a voltage comparator and a metal-oxide-semiconductor field-effect transistor (MOS transistor for short), or a mature direct current/direct current (DC/DC) chip is directly used. However, the two voltage detection circuits require a large number of capacitors, inductors, resistors and other devices, so that the purchase capital cost is high, and the design goals of miniaturization and low power consumption of the voltage detection circuit are not met; in addition, the two voltage detection circuits have slow response speed, and are not suitable for service scenes with high requirements on response speed.

In summary, a voltage detection circuit for voltage control with low capital cost and high response speed is needed.

Disclosure of Invention

The present invention provides a voltage detection circuit for realizing voltage control with low capital cost and high response speed.

In a first aspect, the present invention provides a voltage detection circuit, including: the low-voltage processing circuit and the high-voltage processing circuit are coupled with the low-voltage processing circuit and are realized through a switch unit; the input end of the low-voltage processing circuit is connected with a power supply, and the output end of the high-voltage processing circuit is connected with a load; a low voltage processing circuit for limiting an input voltage of the power supply to flow into the high voltage processing circuit when the input voltage is below a low voltage threshold; and the high-voltage processing circuit is used for reducing the input voltage when the input voltage of the power supply is higher than the high-voltage threshold value and outputting the reduced input voltage to the load.

In the embodiment of the invention, by arranging the low-voltage processing circuit and the high-voltage processing circuit coupled with the low-voltage processing circuit in the voltage detection circuit, when the input voltage of the power supply is lower than the low-voltage threshold, the input voltage is limited to flow into the high-voltage processing circuit through the low-voltage processing circuit so as to avoid the voltage from flowing into the load, that is, when the input voltage of the power supply is lower than the low-voltage threshold, the load is in a rest state; furthermore, the low voltage processing circuit allows the input voltage to flow into the high voltage processing circuit when the input voltage of the power supply is higher than the low voltage threshold and lower than the high voltage threshold, and the high voltage processing circuit allows the voltage to flow into the load, that is, when the input voltage of the power supply is higher than the low voltage threshold and lower than the high voltage threshold, the load is in an operating state; when the input voltage of the power supply is higher than the high-voltage threshold, the high-voltage processing circuit may step down the input voltage and output the stepped-down input voltage to the load. In the above scheme, since the low-voltage processing circuit and the high-voltage processing circuit have low capital cost and high response speed, the scheme can realize the control of the voltage with low capital cost and high response speed.

In an optional manner, the low voltage processing circuit includes a transient suppression diode TVS, a first end of the TVS is an input end of the low voltage processing circuit, and a second end of the TVS is connected to an input end of the high voltage processing circuit; the difference value between the conduction voltage of the TVS and the low-voltage threshold is within a preset range.

In the embodiment of the invention, the TVS can limit the voltage rise in a short time, so that the voltage detection circuit can be protected from transient high-voltage impact, such as high-voltage impact on the voltage detection circuit caused by mistaken touch. In addition, the TVS has the characteristics of quick response and high impedance, and the purchase capital cost of the TVS is lower.

In an alternative mode, the high-voltage processing circuit comprises a current limiter, a control electrode of the current limiter is connected with the output end of the low-voltage processing circuit, a first electrode of the current limiter is used for being grounded, and a second electrode of the current limiter is used for being connected with the output end of the high-voltage processing circuit; and the current limiter is used for limiting the current flowing into the high-voltage processing circuit within a preset current range when the input voltage is higher than the high-voltage threshold value.

In the embodiment of the invention, as the current limiter is arranged in the high-voltage processing circuit, the current limiter can limit the current flowing into the high-voltage processing circuit within a preset current range when the input voltage is higher than the high-voltage threshold value. Therefore, when the input voltage of the power supply is higher than the high voltage threshold, the current limiter can output stable current to the high voltage processing circuit.

In an alternative mode, the current limiter includes a negative anode and negative electrode transistor NPN, a base of the NPN is a control electrode of the current limiter, an emitter of the NPN is a first electrode of the current limiter, and a collector of the NPN is a second electrode of the current limiter.

In an embodiment of the present invention, the NPN transistor can control the current flow. When the input voltage is higher than the high-voltage threshold value, the NPN tube is in a saturated state. The collector current of the saturated NPN tube no longer increases with the increase in the base current, but is rather near a fixed value. Therefore, when the input voltage is higher than the high-voltage threshold value, the collector of the NPN tube can output stable current to the high-voltage processing circuit.

In an optional mode, the high voltage processing circuit further comprises a first resistor; the first end of the first resistor is grounded, and the second end of the first resistor is connected with the emitter of the NPN.

In the embodiment of the invention, the first resistor is arranged in the high-voltage processing circuit, so that the current of the emitter can be limited, the overcurrent of the emitter is avoided, and the NPN damage is effectively prevented. In addition, the first resistor can help eliminate the capacitance effect in the NPN, so that the stability of the output current and the output voltage of the NPN is higher, and the stability of the high-voltage processing circuit is improved.

In an optional mode, the high-voltage processing circuit further comprises a voltage difference forming circuit and a field-effect tube; the input end of the differential pressure forming circuit is respectively connected with the second electrode of the current limiter and the control electrode of the field-effect tube, the output end of the differential pressure forming circuit is connected with the first electrode of the field-effect tube, and the second electrode of the field-effect tube is the output end of the high-voltage processing circuit; a voltage difference forming circuit for forming a voltage difference between the first electrode and the control electrode of the field effect tube according to the current from the current limiter; and the field effect tube is used for conducting the second electrode of the field effect tube and the first electrode of the field effect tube according to the voltage difference.

In the embodiment of the invention, by arranging the voltage difference forming circuit in the high-voltage processing circuit, a voltage difference can be formed between the first electrode and the control electrode of the field effect tube according to the current from the current limiter; and conducting the field effect transistor according to the voltage difference, so that the field effect transistor outputs the voltage to the load.

In an alternative form, the voltage difference formation circuit includes a second resistor and a voltage converter; the first end of the second resistor is the input end of the voltage difference forming circuit, the second end of the second resistor is connected with the input end of the voltage converter, and the output end of the voltage converter is the output end of the voltage difference forming circuit.

In the embodiment of the present invention, a voltage difference is formed between the input terminal and the output terminal of the voltage difference forming circuit by providing the second resistor and the voltage converter in the voltage difference forming circuit.

In an optional mode, the field-effect transistor is a P-type metal oxide semiconductor PMOS transistor, a gate of the PMOS transistor is a control electrode of the field-effect transistor, a source of the PMOS transistor is a first electrode of the field-effect transistor, and a drain of the PMOS transistor is a second electrode of the field-effect transistor.

In the embodiment of the invention, the PMOS tube is used for controlling the current flow in the circuit. When the voltage between the grid electrode and the source electrode of the PMOS is larger than the starting voltage of the PMOS, the PMOS is conducted and outputs voltage to the load.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments will be briefly introduced below, and it is apparent that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings may be obtained based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of a voltage detection circuit according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a high voltage processing circuit according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a voltage difference generation circuit according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a possible voltage detection circuit according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a response time of a voltage detection circuit according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Moreover, based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terms "first", "second", etc. in the present invention are used for distinguishing similar objects, and are not necessarily used for describing a particular order or sequence. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the disclosure described herein are capable of operation in sequences other than those illustrated or described herein. The implementations described in the following exemplary examples do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.

As described in the background, the voltage detection circuit in the prior art has a high capital cost for purchase and a slow response speed.

In view of the above, embodiments of the present invention provide a voltage detection circuit for implementing voltage control with low capital cost and high response speed.

Fig. 1 is a schematic diagram of a voltage detection circuit according to an embodiment of the present invention. The voltage detection circuit includes: a low voltage processing circuit and a high voltage processing circuit coupled to the low voltage processing circuit. Wherein the low voltage processing circuit and the high voltage processing circuit are realized by a switch unit. The input end A1 of the low-voltage processing circuit is connected with a power supply, and the output end A2 of the low-voltage processing circuit is connected with the input end B1 of the high-voltage processing circuit; the output end B2 of the high-voltage processing circuit is connected with a load.

Specifically, the low voltage processing circuit is configured to limit the input voltage to flow into the high voltage processing circuit when the input voltage of the power supply is below a low voltage threshold. When the input voltage of the power supply is lower than the low-voltage threshold, the voltage detection circuit limits the voltage to flow into the load, so that the load is in a rest state. It should be noted that the value of the low voltage threshold is related to the type of the load connected to the voltage detection circuit, and the low voltage threshold of the voltage detection circuit may be different for different types of loads.

The high-voltage processing circuit is used for reducing the input voltage when the input voltage of the power supply is higher than a high-voltage threshold value, and outputting the reduced input voltage to a load. When the input voltage of the power supply is higher than the low-voltage threshold, the voltage detection circuit reduces the input voltage and outputs the reduced input voltage to a load. It should be noted that the value of the high voltage threshold is related to the type of the load connected to the voltage detection circuit, and the high voltage threshold of the voltage detection circuit may be different for different types of loads.

In one possible embodiment, the low Voltage processing circuit includes a Transient Voltage Suppression Diode (TVS), the first terminal of the TVS is an input terminal of the low Voltage processing circuit, and the second terminal of the TVS is connected to an input terminal of the high Voltage processing circuit. The difference value between the conduction voltage of the TVS and the low-voltage threshold is within a preset range.

In detail, the TVS is a special diode, and has characteristics of fast response and high impedance. The working principle is as follows: when the external voltage exceeds the turn-on voltage of the TVS (i.e., the breakdown voltage of the TVS), the TVS is rapidly activated and turned on, so that a current flows, thereby limiting the increase of the voltage. When the voltage is reduced to the normal range, the TVS is automatically turned off. It should be noted that the turn-on voltage of the TVS depends on the structure, material and manufacturing process of the TVS. Generally, the higher the turn-on voltage of a TVS, the greater its impedance, so that sensitive circuits can be better protected from transient voltage surges.

In this scheme, because low-voltage processing circuit and high-voltage processing circuit can consume a part of voltage, consequently, TVS's turn-on voltage is unequal with predetermined low-voltage threshold, and TVS's turn-on voltage often slightly is less than predetermined low-voltage threshold, in other words, TVS's turn-on voltage and low-voltage threshold's difference lie in predetermineeing the within range. For example, the low voltage threshold is 5.4v, the turn-on voltage of the TVS may be 4.5v, and the difference between the turn-on voltage of the TVS and the low voltage threshold is 0.9v.

In one possible embodiment, the high voltage processing circuit comprises a current limiter.

Fig. 2 is a schematic diagram of a high voltage processing circuit according to an embodiment of the invention. The control electrode D1 of the current limiter is connected with the output end of the low-voltage processing circuit, the first electrode D2 of the current limiter is used for being grounded, and the second electrode D3 of the current limiter is used for being connected with the output end of the high-voltage processing circuit. The current limiter is used for limiting the current flowing into the high-voltage processing circuit within a preset current range when the input voltage is higher than the high-voltage threshold value.

In one possible embodiment, the current limiter comprises a negative-polarity, positive-negative transistor (NPN). The base electrode of the NPN is a control electrode of the current limiter, the emitter electrode of the NPN is a first electrode of the current limiter, and the collector electrode of the NPN is a second electrode of the current limiter.

In detail, NPN is a common type of transistor, wherein N represents N-type semiconductor material, P represents P-type semiconductor material, and N represents N-type semiconductor material. The NPN is comprised of two P-type semiconductor materials and one N-type semiconductor material, where the two P-type semiconductor materials surround the N-type semiconductor material. The operating principle of the NPN is based on the electron transport properties of the semiconductor material: in the forward bias state of the NPN transistor, a large number of holes (holes) are generated in the N-type semiconductor material following the PN junction. These holes move to the P-type semiconductor material and create an electrical current between the two materials. The NPN tube has three electrodes: a control electrode (also known as base), a collector, and an emitter.

NPN has three states: amplification state, cut-off state, saturation state. When the control electrode current increases to a certain extent, the NPN is in saturation. In the saturation state, the voltage of the control electrode is greater than the voltage of the emitter electrode, which is greater than the voltage of the collector electrode. The collector current of the NPN in the saturation state no longer increases with an increase in the control electrode current, but does not change so much in the vicinity of a certain value, and at this time, the NPN control current flows, the voltage between the collector and the emitter is small (usually less than 0.6 v), and the on state of the switch is equivalent between the collector and the emitter.

In one possible embodiment, the high voltage processing circuit further comprises a first resistor.

As shown in fig. 2, a first terminal E1 of the first resistor is grounded, and a second terminal E2 of the first resistor is connected to the emitter of the NPN.

In one possible embodiment, the high voltage processing circuit further comprises a voltage difference forming circuit and a field effect transistor.

As shown in fig. 2, the input terminal F1 of the voltage difference forming circuit is connected to the second electrode D3 of the current limiter and the control electrode J1 of the fet, respectively, the output terminal F2 of the voltage difference forming circuit is connected to the first electrode J2 of the fet, and the second electrode J3 of the fet is the output terminal of the high-voltage processing circuit.

In detail, the voltage difference forming circuit is configured to form a voltage difference between the first electrode and the control electrode of the field effect tube according to a current from the current limiter. The field effect transistor is used for conducting the second electrode of the field effect transistor and the first electrode of the field effect transistor according to the voltage difference.

A Field Effect Transistor (FET), which is also called a Field Effect Transistor (FET), belongs to a voltage control type semiconductor device, and controls an output loop current by controlling an electric field effect of an input loop. Generally, a field effect transistor includes three terminals, a gate (gate, G), a drain (drain, D), and a source (source, S). The gate may also be referred to as a control electrode. In which the grid is a mesh-like or spiral electrode composed of metal filaments, which can be considered as a switch, also called control electrode, controlling a physical grid. The gate may allow or block the flow of electrons by creating or eliminating a channel between the source and drain. The field effect transistor can be classified into a junction field effect transistor (jfet) and a metal-oxide-semiconductor field-effect transistor (MOS) according to its type. A junction field-effect transistor (JFET) is a three-terminal active device with an amplifying function, and is the simplest one of unipolar field-effect transistors. The MOS transistor is widely applied to analog circuits and digital circuits.

In one possible embodiment, the voltage difference forming circuit comprises a second resistor and a voltage converter.

Fig. 3 is a schematic diagram of a voltage difference forming circuit according to an embodiment of the present invention. The first end K1 of the second resistor is an input end of the voltage difference forming circuit, the second end K2 of the second resistor is connected with the input end L1 of the voltage converter, and the output end L2 of the voltage converter is an output end of the voltage difference forming circuit.

In detail, the voltage converter is used to convert one voltage into another voltage.

In one possible embodiment, the voltage converter may be a direct-current-to-direct-current (DC-DC) voltage converter, which is used to adjust the input DC voltage to a desired voltage. Specifically, the dc-to-dc voltage converter includes a motor-driven inverter, a bridge rectifier, and a flyback rectifier. The motor-driven frequency converter adjusts the voltage by adjusting the frequency of the motor. The bridge rectifier regulates the voltage by converting alternating current to direct current and by regulating a resistor. The flyback rectifier converts alternating current into direct current by using an inductor and a capacitor, and adjusts voltage by adjusting an induced current.

In the embodiment of the invention, because the output end L2 of the voltage converter is connected with the first electrode of the field effect transistor, the voltage of the first electrode of the field effect transistor can be always maintained at a fixed value when the voltage detection circuit is conducted by using the voltage converter.

In one possible embodiment, the field effect transistor is a P-type metal oxide semiconductor PMOS transistor, the gate of the PMOS transistor is a control electrode of the field effect transistor, the source of the PMOS transistor is a first electrode of the field effect transistor, and the drain of the PMOS transistor is a second electrode of the field effect transistor.

In the embodiment of the invention, the PMOS tube is used for controlling the current flowing in the circuit. When the voltage between the grid electrode and the source electrode of the PMOS is larger than the starting voltage of the PMOS, the PMOS is conducted and outputs voltage to the load.

The MOS transistor is one type of Field Effect Transistor (FET) and includes three terminals, a gate, a drain, and a source. For a detailed description of the gate, the drain and the source of the MOS transistor, reference may be made to the description of the gate, the drain and the source of the field effect transistor, and detailed description thereof is omitted here. The MOS transistors can be classified into N-channel type and P-channel type according to the channel polarity. The N-channel type is generally referred to as NMOS, respectively, and the P-channel type is generally referred to as PMOS, respectively. The MOS transistor is often used as an electronic switch, and the conduction condition is that a forward voltage is applied between a gate and a source of the MOS transistor, and when the forward voltage is greater than a turn-on voltage of the MOS transistor, the MOS transistor is activated to conduct, so as to achieve current conduction. Normally, the turn-on voltage of the MOS transistor is about 5V.

Fig. 4 is a schematic diagram of a possible voltage detection circuit according to an embodiment of the present invention. The actual circuit comprises a power supply, a low voltage processing circuit 401, a current limiter 402, a first resistor 403, a second resistor 404, a voltage converter 405, a field effect transistor 406, and a load. The input end of the low-voltage processing circuit 401 is connected to a power supply, the output end of the low-voltage processing circuit 401 is connected to the control electrode of the current limiter 402, the first electrode of the current limiter 402 is connected to the second end of the first resistor 403, the first end of the first resistor 403 is grounded, the second electrode of the current limiter 402 is respectively connected to the first end of the second resistor 404 and the control electrode of the field-effect transistor 406, the second end of the second resistor 404 is connected to the input end of the voltage converter 405, the output end of the voltage converter 405 is connected to the source electrode of the field-effect transistor 406, and the drain electrode of the field-effect transistor 406 is connected to a load.

Referring now to fig. 4, each of the components in the voltage detection circuit will be described:

in one example, the low voltage processing circuit 401 may include a TVS (N1 in fig. 4) for limiting the input voltage to the high voltage processing circuit when the input voltage of the power supply is below the low voltage threshold. For a detailed description of the TVS, reference is made to the related description above, and further description is omitted here.

In one example, the current limiter 402 may include an NPN (P1 in fig. 4) for limiting the current flowing into the high voltage processing circuit within a predetermined current range when the input voltage is higher than the high voltage threshold. For the detailed description of the NPN, reference is made to the related description above, and the detailed description is omitted here.

In one example, the first resistor 403 may include a resistor (R1 in fig. 4) for protecting the current limiter 402.

In one example, the second resistor 404 may include a resistor (R2 in fig. 4) for forming the voltage difference.

In one example, the voltage converter 405 may include a DC-DC voltage converter (O1 in fig. 4) to form the voltage difference.

In one example, the fet 406 may comprise a PMOS transistor, and when the voltage difference between the source and the base of the PMOS transistor is greater than the turn-on voltage, the PMOS transistor is turned on to output a voltage to the load. For a detailed description of the PMOS transistor, reference is made to the related description above, and the detailed description is omitted here.

Taking the example that the turn-on voltage of the TVS is 4.5v and the low voltage threshold of the voltage detection circuit is 5.4v, when the voltage of 4v is inputted from the power supply, the TVS is not turned on because the input voltage of 4v is lower than the turn-on voltage of the TVS, and the voltage detection circuit does not output the voltage to the load, so the load is in a rest state. When the voltage input by the power supply is 5.4v, the TVS is turned on because the input voltage of 5.4v is higher than the turn-on voltage of the TVS, and the NPN is turned on because the potential of the point a is about 5v and is greater than the turn-on voltage of the NPN. The current flows into the NPN, the base of the NPN is conducted to the emitter of the NPN, the collector of the NPN is also conducted to the emitter of the NPN, and the current flows out from the collector of the NPN. The potential at point b is around 4v, that is, the potential at point c is around 4 v. The current flows through the second resistor, the potential of the point d is about 3.3v, and then the current passes through the voltage converter, the voltage converter boosts the voltage and stably outputs 5v, so that the potential of the point e is 5v, namely, the potential of the point f is 5v. For the PMOS tube, the potential of the control electrode is about 4v which is the potential of the point c, and the potential of the source electrode is about 5v which is the potential of the point f, so that a voltage difference is formed between the source electrode of the PMOS tube and the control electrode, the PMOS tube is conducted, the drain electrode of the PMOS tube outputs current to a load, and the output current can reach more than 3A.

It is to be noted thatWhen the voltage of the power input is 5.4v, the voltage is slightly higher than the turn-on voltage of the TVS, because the TVS can be operated at 10 degrees ^-12 Response speed of second order is conducted, so that the switching time delay of the whole voltage detection circuit is mainly determined by NPN and PMOS tubes. The time delay of the conduction of the common NPN and PMOS tubes is only in microsecond level, so the switching time of the voltage detection circuit in the scheme is also in microsecond level.

Fig. 5 is a schematic diagram of a response time of a voltage detection circuit according to an embodiment of the present invention. In the voltage detection circuit, the breakdown voltage of the TVS is 4.5V, the voltage of the power input is 5.4V, and as can be seen from fig. 5, the response time of the entire voltage detection circuit is only about 900 microseconds.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A voltage detection circuit, comprising:

the low-voltage processing circuit and the high-voltage processing circuit are coupled with the low-voltage processing circuit and are realized through a switch unit;

the input end of the low-voltage processing circuit is connected with a power supply, and the output end of the high-voltage processing circuit is connected with a load;

the low-voltage processing circuit is used for limiting the input voltage of the power supply to flow into the high-voltage processing circuit when the input voltage is lower than a low-voltage threshold value;

the high-voltage processing circuit is used for reducing the input voltage of the power supply when the input voltage is higher than a high-voltage threshold value, and outputting the reduced input voltage to the load.

2. The voltage detection circuit of claim 1,

the low-voltage processing circuit comprises a transient suppression diode (TVS), the first end of the TVS is the input end of the low-voltage processing circuit, and the second end of the TVS is connected with the input end of the high-voltage processing circuit;

and the difference value between the conduction voltage of the TVS and the low-voltage threshold is within a preset range.

3. The voltage detection circuit of claim 2,

the high-voltage processing circuit comprises a current limiter, a control electrode of the current limiter is connected with the output end of the low-voltage processing circuit, a first electrode of the current limiter is used for being grounded, and a second electrode of the current limiter is used for being connected with the output end of the high-voltage processing circuit;

and the current limiter is used for limiting the current flowing into the high-voltage processing circuit within a preset current range when the input voltage is higher than the high-voltage threshold value.

4. The voltage detection circuit of claim 3,

the current limiter comprises a negative anode and negative cathode transistor NPN, the base of the NPN is a control electrode of the current limiter, the emitter of the NPN is a first electrode of the current limiter, and the collector of the NPN is a second electrode of the current limiter.

5. The voltage detection circuit of claim 4, wherein the high voltage processing circuit further comprises a first resistor;

the first end of the first resistor is grounded, and the second end of the first resistor is connected with the emitter of the NPN.

6. The voltage detection circuit according to any one of claims 3 to 5, wherein the high voltage processing circuit further comprises a voltage difference forming circuit and a field effect transistor;

the input end of the differential pressure forming circuit is respectively connected with the second electrode of the current limiter and the control electrode of the field-effect tube, the output end of the differential pressure forming circuit is connected with the first electrode of the field-effect tube, and the second electrode of the field-effect tube is the output end of the high-voltage processing circuit;

the voltage difference forming circuit is used for forming a voltage difference between the first electrode and the control electrode of the field effect transistor according to the current from the current limiter;

and the field effect transistor is used for conducting the second electrode of the field effect transistor and the first electrode of the field effect transistor according to the voltage difference.

7. The voltage detection circuit of claim 6,

the voltage difference forming circuit comprises a second resistor and a voltage converter;

the first end of the second resistor is the input end of the differential pressure forming circuit, the second end of the second resistor is connected with the input end of the voltage converter, and the output end of the voltage converter is the output end of the differential pressure forming circuit.

8. The voltage detection circuit of claim 7,

the field effect transistor is a P-type metal oxide semiconductor (PMOS) transistor, a grid electrode of the PMOS transistor is a control electrode of the field effect transistor, a source electrode of the PMOS transistor is a first electrode of the field effect transistor, and a drain electrode of the PMOS transistor is a second electrode of the field effect transistor.