Negative voltage measuring circuit and positive and negative voltage measuring circuit

Abstract

The embodiment of the utility model provides a negative voltage measuring circuit and a positive and negative voltage measuring circuit, and the circuit comprises a voltage conversion circuit, a protection circuit, and a unipolar analog-to-digital converter, the voltage conversion circuit is coupled with a negative voltage input signal or a positive and negative voltage input signal, and the protection circuit is coupled with the unipolar analog-to-digital converter. The single-power operational amplifier is used for converting a received signal into a positive voltage signal according to the single-power operational amplifier; the input end of the unipolar analog-to-digital converter is coupled with the output end of the voltage conversion circuit, and the unipolar analog-to-digital converter is used for collecting the positive voltage signal and measuring the voltage value of the negative voltage input signal or the positive and negative voltage input signal; the protection circuit is respectively coupled with the output end of the voltage conversion circuit and the input end of the unipolar analog-to-digital converter, and is used for controlling the voltage value of the positive voltage signal within the input voltage range of the unipolar analog-to-digital converter so as to protect the unipolar analog-to-digital converter.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of digital circuit technology, and in particular, to a negative voltage measurement circuit and a positive and negative voltage measurement circuit. Background Art

[0002] Typically, digital circuit systems only have a few fixed positive voltages, such as 5V, 3.3V, and 1.2V. If a digital circuit system needs to measure negative voltages, it cannot be directly measured. For this situation, existing technical solutions include adding a negative voltage power supply, a dual-supply op amp, and a bipolar analog-to-digital converter (ADC). The dual-supply op amp receives the negative voltage to be measured, and then the bipolar ADC detects the output of the dual-supply op amp to achieve negative voltage measurement.

[0003] When applying the above-mentioned prior art solution to measure negative voltage, the inventors found that the prior art solution required the addition of a negative voltage power supply, a dual-power supply operational amplifier, and a bipolar ADC, which greatly increased the circuit complexity and cost of the original digital circuit system. Utility Model Content

[0004] The embodiments described herein provide a negative voltage measurement circuit and a positive and negative voltage measurement circuit to address the problem that existing negative voltage measurement solutions increase circuit complexity and cost of digital circuit systems.

[0005] According to a first aspect of the present disclosure, a negative voltage measurement circuit is provided, comprising: a voltage conversion circuit, a protection circuit, and a unipolar analog-to-digital converter, wherein the voltage conversion circuit is coupled to a negative voltage input signal, and is used to convert the negative voltage input signal into a positive voltage signal according to a single-power supply operational amplifier; the input end of the unipolar analog-to-digital converter is coupled to the output end of the voltage conversion circuit, and is used to collect the positive voltage signal and measure the voltage value of the negative voltage input signal; the protection circuit is respectively coupled to the output end of the voltage conversion circuit and the input end of the unipolar analog-to-digital converter, and is used to control the voltage value of the positive voltage signal within the input voltage range of the unipolar analog-to-digital converter to protect the unipolar analog-to-digital converter.

[0006] Optionally, the voltage conversion circuit includes: the single-power supply operational amplifier, a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein the negative input terminal of the single-power supply operational amplifier is respectively coupled to one end of the first resistor and one end of the second resistor, the other end of the first resistor is coupled to the negative voltage input signal, the other end of the second resistor is coupled to the output terminal of the single-power supply operational amplifier, the positive input terminal of the single-power supply operational amplifier is respectively coupled to one end of the third resistor and one end of the fourth resistor, the other end of the third resistor is coupled to the first reference voltage, and the other end of the fourth resistor is coupled to the ground terminal; the output terminal of the single-power supply operational amplifier is the output terminal of the voltage conversion circuit.

[0007] Optionally, the protection circuit includes: a first diode and a second diode, wherein the cathode of the first diode and the anode of the second diode are both coupled to the output end of the voltage conversion circuit, the anode of the first diode is coupled to the second reference voltage, and the cathode of the second diode is coupled to the third reference voltage.

[0008] Optionally, the resistance of the third resistor is equal to the resistance of the first resistor, and the resistance of the fourth resistor is equal to the resistance of the second resistor.

[0009] Optionally, the first reference voltage is equal to the voltage value of the ground terminal.

[0010] Optionally, the second reference voltage is equal to a lower limit value of an input voltage range of the unipolar analog-to-digital converter, and the third reference voltage is equal to an upper limit value of the input voltage range of the unipolar analog-to-digital converter.

[0011] Optionally, the unipolar analog-to-digital converter is a unipolar analog-to-digital converter in a single-chip microcomputer.

[0012] According to a second aspect of the present disclosure, a positive and negative voltage measurement circuit is provided, which includes: a voltage conversion circuit, a protection circuit, and a unipolar analog-to-digital converter, wherein the voltage conversion circuit is coupled to positive and negative voltage input signals, and is used to convert the positive and negative voltage input signals into positive voltage signals according to a single-power supply operational amplifier; the input end of the unipolar analog-to-digital converter is coupled to the output end of the voltage conversion circuit, and is used to collect the positive voltage signal and measure the voltage values ​​of the positive and negative voltage input signals; the protection circuit is respectively coupled to the output end of the voltage conversion circuit and the input end of the unipolar analog-to-digital converter, and is used to control the voltage value of the positive voltage signal within the input voltage range of the unipolar analog-to-digital converter to protect the unipolar analog-to-digital converter.

[0013] Optionally, the voltage conversion circuit includes: the single-power supply operational amplifier, a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein the negative input terminal of the single-power supply operational amplifier is coupled to one end of the first resistor and one end of the second resistor respectively, the other end of the first resistor is coupled to the positive and negative voltage input signals, the other end of the second resistor is coupled to the output terminal of the single-power supply operational amplifier, the positive input terminal of the single-power supply operational amplifier is coupled to one end of the third resistor and one end of the fourth resistor respectively, the other end of the third resistor is coupled to the first reference voltage, and the other end of the fourth resistor is coupled to the ground terminal; the output terminal of the single-power supply operational amplifier is the output terminal of the voltage conversion circuit; the resistance value of the third resistor is equal to the first resistor. The resistance of the fourth resistor is equal to the resistance of the second resistor, and the first reference voltage is a preset positive reference voltage; the protection circuit includes: a first diode and a second diode, wherein the cathode of the first diode and the anode of the second diode are both coupled to the output end of the voltage conversion circuit, the anode of the first diode is coupled to the second reference voltage, and the cathode of the second diode is coupled to the third reference voltage. The input voltage range of the unipolar analog-to-digital converter is the input voltage range of the unipolar analog-to-digital converter, the second reference voltage is equal to the lower limit of the input voltage range of the unipolar analog-to-digital converter, and the third reference voltage is equal to the upper limit of the input voltage range of the unipolar analog-to-digital converter.

[0014] Optionally, the unipolar analog-to-digital converter is a unipolar analog-to-digital converter in a single-chip microcomputer.

[0015] The negative voltage measurement circuit and the positive and negative voltage measurement circuit of the embodiment of the present disclosure include a voltage conversion circuit, a protection circuit, and a unipolar analog-to-digital converter, wherein the voltage conversion circuit is coupled to a negative voltage input signal or a positive and negative voltage input signal, and is used to convert the negative voltage input signal or the positive and negative voltage input signal into a positive voltage signal according to a single-power operational amplifier; the input end of the unipolar analog-to-digital converter is coupled to the output end of the voltage conversion circuit, and is used to collect the positive voltage signal and measure the voltage value of the negative voltage input signal or the positive and negative voltage input signal; the protection circuit is respectively coupled to the output end of the voltage conversion circuit and the input end of the unipolar analog-to-digital converter, and is used to control the voltage value of the positive voltage signal to be within the input voltage range of the unipolar analog-to-digital converter to protect the unipolar analog-to-digital converter. It can be seen that the circuit for measuring negative voltage in the embodiment of the present disclosure does not require a dual-power operational amplifier or a bipolar analog-to-digital converter, and therefore does not require an additional negative voltage power supply. Only a single-power operational amplifier and a unipolar analog-to-digital converter are required, which is simpler and less expensive than existing negative voltage measurement solutions. In addition, the unipolar analog-to-digital converter can be protected by a protection circuit, thereby improving the stability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It should be noted that the drawings described below only relate to some embodiments of the present disclosure and are not intended to limit the present disclosure.

[0017] Figure 1 A schematic block diagram of a negative voltage measurement circuit according to an embodiment of the present disclosure is shown;

[0018] Figure 2 An exemplary circuit diagram of a negative voltage measurement circuit according to an embodiment of the present disclosure is shown;

[0019] Figure 3 An exemplary circuit diagram of a positive and negative voltage measurement circuit according to an embodiment of the present disclosure is shown;

[0020] Elements in the drawings are schematic and not drawn to scale. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0022] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal manner unless otherwise explicitly defined herein. As used herein, a statement that two or more parts are "connected" or "coupled" together shall mean that the parts are joined together either directly or through one or more intermediate components.

[0023] In all embodiments of the present disclosure, terms such as “first” and “second” are used only to distinguish one component (or a part of a component) from another component (or another part of a component).

[0024] To address the problem of existing negative voltage measurement solutions increasing the circuit complexity and cost of digital circuit systems, a new negative voltage measurement circuit is proposed. The negative voltage measurement circuit of the disclosed embodiment eliminates the need for a negative power supply and utilizes a single-power op amp and a unipolar analog-to-digital converter (ADC) to measure negative voltages. This circuit structure is simple and low-cost. The following describes the disclosed negative voltage measurement circuit in detail.

[0025] Figure 1 FIG. 1 shows a schematic block diagram of a negative voltage measurement circuit 100 according to an embodiment of the present disclosure. Figure 1 As shown, the negative voltage measurement circuit 100 includes: a voltage conversion circuit 110 , a protection circuit 120 , and a unipolar analog-to-digital converter 130 .

[0026] The voltage conversion circuit 110 is coupled to a negative voltage input signal Vin and is configured to convert the negative voltage input signal Vin into a positive voltage signal Vo using a single-supply operational amplifier. The single-supply operational amplifier is powered by a single power supply, i.e., the positive terminal supplies a positive voltage and the negative terminal supplies a zero voltage. This eliminates the need for a negative voltage power supply for digital circuit systems with only a few fixed positive voltages, thereby reducing costs. Furthermore, the voltage converter in the disclosed embodiment utilizes the principle of inverting amplification to convert the negative voltage input signal Vin into a positive voltage signal Vo. This conversion into a positive voltage signal Vo enables measurement by the unipolar analog-to-digital converter 130. If the converted signal remains a negative voltage, a bipolar analog-to-digital converter is required. In actual digital circuit systems, such as microcontrollers, unipolar analog-to-digital converters are often used. This necessitates the addition of a bipolar analog-to-digital converter, increasing circuit complexity and cost. In the embodiment of the present disclosure, after the negative voltage input signal Vin is converted into a positive voltage signal Vo, the voltage can be directly measured using the built-in unipolar analog-to-digital converter in the digital circuit system, which is very convenient and can save costs.

[0027] The input end of the unipolar analog-to-digital converter 130 is coupled to the output end of the voltage conversion circuit 110, and is used to collect the positive voltage signal Vo and measure the voltage value of the negative voltage input signal Vin. The unipolar analog-to-digital converter 130 refers to a power supply with only a positive voltage. The unipolar analog-to-digital converter 130 is used to collect the output voltage Vo (analog signal) of the voltage conversion circuit 110 and convert it into a digital signal for use by the digital circuit system. It should be noted that the positive voltage signal Vo directly collected by the unipolar analog-to-digital converter 130 cannot represent the voltage value of the negative voltage input signal Vin to be measured. Therefore, it is necessary to multiply the positive voltage signal Vo by a proportional coefficient. The proportional coefficient is the reciprocal of the amplification ratio of the voltage conversion circuit 110.

[0028] Protection circuit 120 is coupled to the output terminal of voltage conversion circuit 110 and the input terminal of unipolar analog-to-digital converter 130, respectively, and is configured to control the voltage value of positive voltage signal Vo within the input voltage range of unipolar analog-to-digital converter 130, thereby protecting unipolar analog-to-digital converter 130. The principle of protection circuit 120 is that when the positive voltage signal Vo output by voltage conversion circuit 110 is not within the input voltage range of unipolar analog-to-digital converter 130 (less than the lower limit of the input voltage range, or greater than the upper limit of the input voltage range), it can be controlled within the input voltage range to prevent damage to unipolar analog-to-digital converter 130. Specifically, protection circuit 120 may be a diode protection circuit, which utilizes the unidirectional conductivity of the diode to limit the voltage value of positive voltage signal Vo.

[0029] As can be seen from the above description, the negative voltage measurement circuit 100 in the disclosed embodiment does not require a dual-supply operational amplifier or a bipolar analog-to-digital converter. Consequently, there is no need for an additional negative voltage power supply. Instead, only a single-supply operational amplifier and a unipolar analog-to-digital converter are required. This makes the negative voltage measurement circuit 100 simpler and more cost-effective than existing negative voltage measurement solutions. Furthermore, a protection circuit can be used to protect the unipolar analog-to-digital converter, improving circuit stability.

[0030] Further, such as Figure 2 As shown, the voltage conversion circuit 110 includes a single-supply operational amplifier 111, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The negative input terminal of the single-supply operational amplifier 111 is coupled to one end of the first resistor R1 and one end of the second resistor R2, respectively. The other end of the first resistor R1 is coupled to a negative voltage input signal Vin. The other end of the second resistor R2 is coupled to the output terminal of the single-supply operational amplifier 111. The positive input terminal of the single-supply operational amplifier 111 is coupled to one end of the third resistor R3 and one end of the fourth resistor R4, respectively. The other end of the third resistor R3 is coupled to a first reference voltage Vref1, and the other end of the fourth resistor R4 is coupled to ground. The output terminal of the single-supply operational amplifier 111 serves as the output terminal of the voltage conversion circuit 110. The first resistor R1 is an input resistor that serves as a reference for proportional amplification. Increasing it can reduce power consumption, while decreasing it can improve stability and response speed. The second resistor R2 is a feedback resistor used to determine the proportional amplification factor. Furthermore, the resistance of the third resistor R3 is equal to the resistance of the first resistor R1, and the resistance of the fourth resistor R4 is equal to the resistance of the second resistor R2. This configuration can reduce system errors caused by feedback from the output of the single-supply operational amplifier 111. Furthermore, the first reference voltage Vref1 is equal to the voltage at the ground terminal. The positive supply voltage of the single-supply operational amplifier is VDD, and the negative supply voltage is ground.

[0031] like Figure 2 As shown, the protection circuit 120 includes a first diode D1 and a second diode D2. The cathode of the first diode D1 and the anode of the second diode D2 are both coupled to the output terminal of the voltage conversion circuit 110. The anode of the first diode D1 is coupled to the second reference voltage Vref2, and the cathode of the second diode D2 is coupled to the third reference voltage Vref3. The second reference voltage Vref2 is equal to the lower limit of the input voltage range of the unipolar analog-to-digital converter 130, and the third reference voltage Vref3 is equal to the upper limit of the input voltage range of the unipolar analog-to-digital converter 130.

[0032] Furthermore, the unipolar analog-to-digital converter 130 in the embodiment of the present disclosure is a unipolar analog-to-digital converter built into the single-chip microcomputer, which can greatly reduce circuit costs.

[0033] Combine Figure 2 The working principle of the negative voltage measurement circuit 100 in the embodiment of the present disclosure is described: To more clearly illustrate the principle of the negative voltage measurement circuit 100 in the embodiment of the present disclosure, a specific example is given. Assuming Vin = -15V, R1 = R3 = 49.9KΩ, R2 = R4 = 8.25KΩ, Vref1 = 0, and the input voltage range of the unipolar analog-to-digital converter 130 is (0, 3V), then Vref2 = 0, Vref3 = 3V, according to the amplification principle of the single-supply operational amplifier 111, it can be obtained:

[0034] Vo=(R2 / R1)*(Vref1-Vin)=-(R2 / R1)*Vin;

[0035] Substituting the above parameter values ​​into the formula, we can get Vo = -(8.25 / 49.9)*(-15V)≈2.5V;

[0036] The voltage collected by the input terminal of the unipolar analog-to-digital converter 130 is 2.5V, which is then multiplied by the proportional coefficient (-49.9 / 8.25) to obtain the voltage value of the negative voltage input signal Vin to be detected, ie -15V.

[0037] As can be seen from the above calculation formula for Vo, Vin and Vo are in antiphase, thus converting a negative voltage input signal Vin into a positive voltage signal Vo. Furthermore, in practical applications, the amplification ratio of the unipolar operational amplifier (OPA), and thus the resistance values ​​of R1-R4, can be determined based on the range of the negative voltage input signal Vin to be measured and the input voltage range of the unipolar ADC 130. Furthermore, the value of VDD can also be determined based on the input voltage range of the unipolar ADC 130. For example, when the input voltage range is (0, 3V), a VDD of 5V is sufficient. Higher VDD voltages increase the price.

[0038] For the protection circuit 120, when Vo is less than Vref2, the first diode D1 is turned on, and after the first diode D1 is turned on, Vo is pulled to Vref2. When Vo is greater than Vref3, the second diode D2 is turned on, and after the second diode D2 is turned on, Vo is pulled to Vref3. In this way, the voltage signal received by the unipolar analog-to-digital converter 130 will not be damaged due to exceeding its own input voltage range.

[0039] In summary, the negative voltage measurement circuit 100 in the disclosed embodiment does not require a dual-power op amp or a bipolar analog-to-digital converter, and therefore does not require an additional negative voltage power supply. Instead, it requires only a single-power op amp and a unipolar analog-to-digital converter. This makes it simpler and more cost-effective than existing negative voltage measurement solutions. Furthermore, a protection circuit can be used to protect the unipolar analog-to-digital converter, improving circuit stability.

[0040] In addition, in practical applications, in order to meet the requirements of detecting both positive and negative voltages, the embodiment of the present disclosure is based on Figure 1-2 The negative voltage measurement circuit 100 in the embodiment further provides a positive and negative voltage measurement circuit 200, such as Figure 3 As shown, the positive and negative voltage measurement circuit 200 also includes: a voltage conversion circuit 110, a protection circuit 120, and a unipolar analog-to-digital converter 130, wherein the voltage conversion circuit 110 is coupled to the positive and negative voltage input signal Vin (that is, Vin can be a positive voltage or a negative voltage), and is used to convert the positive and negative voltage input signal Vin into a positive voltage signal Vo according to a single-power supply operational amplifier; the input end of the unipolar analog-to-digital converter 130 is coupled to the output end of the voltage conversion circuit 110, and is used to collect the positive voltage signal Vo and measure the voltage value of the positive and negative voltage input signal Vin; the protection circuit 120 is respectively coupled to the output end of the voltage conversion circuit 110 and the input end of the unipolar analog-to-digital converter 130, and is used to control the voltage value of the positive voltage signal Vo within the input voltage range of the unipolar analog-to-digital converter 130 to protect the unipolar analog-to-digital converter 130.

[0041] The voltage conversion circuit 110 also includes: a single-power supply operational amplifier 111, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The negative input terminal of the single-power supply operational amplifier 111 is coupled to one end of the first resistor R1 and one end of the second resistor R2, respectively. The other end of the first resistor R1 is coupled to the positive and negative voltage input signals Vin. The other end of the second resistor R2 is coupled to the output terminal of the single-power supply operational amplifier 111. The positive input terminal of the single-power supply operational amplifier 111 is coupled to one end of the third resistor R3 and one end of the fourth resistor R4, respectively. The other end of the third resistor R3 is coupled to the first reference voltage Vref1, and the other end of the fourth resistor R4 is coupled to the ground. The output terminal of the single-power supply operational amplifier 111 is the output terminal of the voltage conversion circuit 110. The resistance of the third resistor R3 is equal to the resistance of the first resistor R1. The resistance of the fourth resistor R4 is equal to the resistance of the second resistor R2. The first reference voltage Vref1 is a preset positive reference voltage V+. The protection circuit 120 includes a first diode D1 and a second diode D2. The cathode of the first diode D1 and the anode of the second diode D2 are both coupled to the output terminal of the voltage conversion circuit 110. The anode of the first diode D1 is coupled to the second reference voltage Vref2, and the cathode of the second diode D2 is coupled to the third reference voltage Vref3. The input voltage range of the unipolar analog-to-digital converter 130 is the input voltage range of the unipolar analog-to-digital converter 130. The second reference voltage Vref2 is equal to the lower limit of the input voltage range of the unipolar analog-to-digital converter 130, and the third reference voltage Vref3 is equal to the upper limit of the input voltage range of the unipolar analog-to-digital converter 130. The unipolar analog-to-digital converter 130 is a unipolar analog-to-digital converter 130 in the microcontroller.

[0042] From the above description we can see that Figure 3 The positive and negative voltage measurement circuit 200 and Figure 1-2 The difference between the negative voltage measurement circuit 100 and the negative voltage measurement circuit 100 is that the voltage value of the first reference voltage Vref1 is different: one is the preset positive reference voltage V+, and the other is the ground terminal, that is, zero voltage. When Vref1 is V+, Vin can be a positive or negative voltage value. Figure 2 The same amplification principle is used in Figure 3 The calculation formula of Vo in is as follows:

[0043] Vo=(R2 / R1)*(Vref1-Vin)

[0044] From this formula, we can see that if Vin is a positive voltage less than Vref1, Vo is still a positive voltage value, and Vin can be measured. Therefore, Figure 3The positive and negative voltage measurement circuit 200 in Figure 2 must ensure that Vin is less than Vref1. For example, if Vref1 is 5V, Vin cannot exceed 5V. In practice, if you want to measure a larger positive voltage, you can set Vref1 higher. The lower limit of Vin (maximum negative voltage) is still determined by the voltage input range of the unipolar ADC 130 and the resistance values ​​of R1-R4.

[0045] In summary, the positive and negative voltage measurement circuit 200 in the embodiment of the present disclosure, in addition to having the effects of the above-mentioned negative voltage measurement circuit 100, can also simultaneously measure positive voltage input signals. Compared with 00, in addition to having the effects of the above-mentioned negative voltage measurement circuit 100, the application range is expanded.

[0046] Unless the context clearly indicates otherwise, as used herein and in the appended claims, the singular includes the plural, and vice versa. Thus, when referring to the singular, the plural of the corresponding term is generally included. Similarly, the words "include" and "comprising" are to be interpreted as inclusive rather than exclusive. Likewise, the terms "include" and "or" should be interpreted as inclusive unless such interpretation is expressly prohibited herein. Where the term "example" is used herein, particularly when it follows a group of terms, "example" is merely exemplary and illustrative and should not be considered exclusive or comprehensive.

[0047] Further aspects and scope of adaptability become apparent from the description provided herein. It should be understood that various aspects of the present disclosure can be implemented individually or in combination with one or more other aspects. It should also be understood that the description and specific embodiments herein are intended to be illustrative only and are not intended to limit the scope of the present disclosure.

[0048] Several embodiments of the present disclosure have been described in detail above, but it is obvious that those skilled in the art can make various modifications and variations to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. The scope of protection of the present disclosure is defined by the appended claims.

Claims

1. A negative voltage measurement circuit, characterized in that: The negative voltage measurement circuit includes: a voltage conversion circuit, a protection circuit, and a unipolar analog-to-digital converter. In which, the voltage conversion circuit is coupled to a negative voltage input signal, and is used to convert the negative voltage input signal into a positive voltage signal according to a single-power operational amplifier; the input end of the unipolar analog-to-digital converter is coupled to the output end of the voltage conversion circuit, and is used to collect the positive voltage signal and measure the voltage value of the negative voltage input signal; the protection circuit is respectively coupled to the output end of the voltage conversion circuit and the input end of the unipolar analog-to-digital converter, and is used to control the voltage value of the positive voltage signal within the input voltage range of the unipolar analog-to-digital converter to protect the unipolar analog-to-digital converter.

2. The negative voltage measurement circuit according to claim 1, wherein: The voltage conversion circuit includes: the single power supply operational amplifier, a first resistor, a second resistor, a third resistor, and a fourth resistor. The negative input terminal of the single-power supply operational amplifier is coupled to one end of the first resistor and one end of the second resistor respectively, the other end of the first resistor is coupled to the negative voltage input signal, the other end of the second resistor is coupled to the output terminal of the single-power supply operational amplifier, the positive input terminal of the single-power supply operational amplifier is coupled to one end of the third resistor and one end of the fourth resistor respectively, the other end of the third resistor is coupled to the first reference voltage, and the other end of the fourth resistor is coupled to the ground terminal; the output terminal of the single-power supply operational amplifier is the output terminal of the voltage conversion circuit.

3. The negative voltage measurement circuit according to claim 2, wherein: The protection circuit includes: a first diode, a second diode, The cathode of the first diode and the anode of the second diode are both coupled to the output end of the voltage conversion circuit, the anode of the first diode is coupled to the second reference voltage, and the cathode of the second diode is coupled to the third reference voltage.

4. The negative voltage measurement circuit according to claim 2, wherein: The resistance of the third resistor is equal to the resistance of the first resistor, and the resistance of the fourth resistor is equal to the resistance of the second resistor.

5. The negative voltage measurement circuit according to claim 4, wherein: The first reference voltage is equal to the voltage value of the ground terminal.

6. The negative voltage measurement circuit according to claim 3, wherein: The second reference voltage is equal to a lower limit value of an input voltage range of the unipolar analog-to-digital converter, and the third reference voltage is equal to an upper limit value of the input voltage range of the unipolar analog-to-digital converter.

7. The negative voltage measurement circuit according to claim 1, wherein: The unipolar analog-to-digital converter is a unipolar analog-to-digital converter in a single-chip microcomputer.

8. A positive and negative voltage measurement circuit, characterized in that: The positive and negative voltage measurement circuit includes: a voltage conversion circuit, a protection circuit, and a unipolar analog-to-digital converter. In which, the voltage conversion circuit is coupled to positive and negative voltage input signals, and is used to convert the positive and negative voltage input signals into positive voltage signals according to a single-power operational amplifier; the input end of the unipolar analog-to-digital converter is coupled to the output end of the voltage conversion circuit, and is used to collect the positive voltage signal and measure the voltage values ​​of the positive and negative voltage input signals; the protection circuit is respectively coupled to the output end of the voltage conversion circuit and the input end of the unipolar analog-to-digital converter, and is used to control the voltage value of the positive voltage signal within the input voltage range of the unipolar analog-to-digital converter to protect the unipolar analog-to-digital converter.

9. The positive and negative voltage measurement circuit according to claim 8, characterized in that: The voltage conversion circuit includes: the single-power operational amplifier, a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein the negative input terminal of the single-power operational amplifier is coupled to one end of the first resistor and one end of the second resistor, respectively, the other end of the first resistor is coupled to the positive and negative voltage input signals, the other end of the second resistor is coupled to the output terminal of the single-power operational amplifier, the positive input terminal of the single-power operational amplifier is coupled to one end of the third resistor and one end of the fourth resistor, the other end of the third resistor is coupled to a first reference voltage, and the other end of the fourth resistor is coupled to ground; the output terminal of the single-power operational amplifier is the output terminal of the voltage conversion circuit; the resistance value of the third resistor is equal to the resistance value of the first resistor, the resistance value of the fourth resistor is equal to the resistance value of the second resistor, and the first reference voltage is a preset positive reference voltage; The protection circuit includes: a first diode and a second diode, wherein the cathode of the first diode and the anode of the second diode are both coupled to the output end of the voltage conversion circuit, the anode of the first diode is coupled to a second reference voltage, and the cathode of the second diode is coupled to a third reference voltage. The input voltage range of the unipolar analog-to-digital converter is the input voltage range of the unipolar analog-to-digital converter, the second reference voltage is equal to the lower limit of the input voltage range of the unipolar analog-to-digital converter, and the third reference voltage is equal to the upper limit of the input voltage range of the unipolar analog-to-digital converter.

10. The positive and negative voltage measurement circuit according to claim 8, characterized in that: The unipolar analog-to-digital converter is a unipolar analog-to-digital converter in a single-chip microcomputer.

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