Digital voltmeter reference calibration voltage division circuit and electronic equipment

Abstract

The utility model provides a digital voltmeter reference calibration voltage division circuit and an electronic device. The circuit comprises an A / D conversion chip and a voltage measurement calibration circuit. The voltage measurement calibration circuit is composed of a reference voltage source circuit, an adjustable potentiometer and a voltage division network with a preset voltage division ratio. One end of the reference voltage source circuit is connected with one end of the adjustable potentiometer, the other end of the adjustable potentiometer is connected with the A / D conversion chip, and the voltage division network with the preset voltage division ratio is connected with the A / D conversion chip; the voltage division network with the preset voltage division ratio comprises an analog switch, a first resistor and a second resistor; the analog switch determines to be connected with one end of the first resistor or connected with one end of the second resistor according to a level signal received by the analog switch; the other end of the first resistor or the other end of the second resistor is connected with the A / D conversion chip. Through accurate reference voltage generation and flexible voltage division network control, the reference calibration voltage division circuit which is stable, accurate and easy to configure is provided for the digital voltmeter.

Description

Technical Field

[0001] The utility model belongs to the technical field of voltage measurement circuits, and in particular relates to a digital voltmeter reference calibration voltage divider circuit and electronic equipment. Background Art

[0002] At present, when measuring voltage, voltmeters or multimeters are commonly used for measurement. In the design of digital voltmeters, an accurate reference voltage is often used for accurate voltage measurement. The design complexity of the reference voltage source circuit is a common problem. In addition, when the input voltage of the digital voltmeter exceeds the tolerance range of the internal circuit, if the voltage divider network is not designed accurately or it is difficult to adapt to all input voltage ranges, the high voltage directly input to the internal circuit of the digital voltmeter may cause damage to circuit components, such as A / D conversion chips, reference voltage sources, protection diodes, etc. This will shorten the service life of the voltmeter and may even cause the voltmeter to fail immediately. Even if the internal circuit is not immediately damaged, the high voltage may cause the circuit performance to degrade, thereby affecting the accuracy of the measurement. Utility Model Content

[0003] In view of the defects of the above-mentioned prior art, the utility model provides a digital voltmeter reference calibration voltage divider circuit and electronic equipment, which can accurately generate and calibrate the reference voltage through the reference voltage source circuit, adjustable potentiometer and other circuit designs, thereby improving the measurement accuracy of the digital voltmeter. The voltage divider network with a preset voltage divider ratio can provide a stable voltage divider ratio, ensure the accurate distribution of the reference voltage, ensure the accuracy of voltage measurement, and protect the circuit safety.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a digital voltmeter reference calibration voltage divider circuit, comprising: an A / D conversion chip; and also comprising a voltage measurement calibration circuit; the voltage measurement calibration circuit is at least composed of a reference voltage source circuit, an adjustable potentiometer and a voltage divider network with a preset voltage divider ratio; wherein one end of the reference voltage source circuit is connected to one end of the adjustable potentiometer, the other end of the adjustable potentiometer is connected to the A / D conversion chip, and the voltage divider network with a preset voltage divider ratio is connected to the A / D conversion chip.

[0005] Among them, the voltage divider network with a preset voltage divider ratio includes at least an analog switch, a first resistor and a second resistor; the analog switch is connected to one end of the first resistor or one end of the second resistor according to the level signal it receives; the other end of the first resistor or the other end of the second resistor is connected to the A / D conversion chip.

[0006] In the utility model, the voltage measurement calibration circuit also includes: a first driver, a second driver and a display screen.

[0007] The A / D conversion chip is connected to one end of the first driver and one end of the second driver respectively; the other end of the first driver and the other end of the second driver are connected to the display screen respectively.

[0008] In the utility model, the voltage measurement calibration circuit further includes: a negative voltage generator and a time base circuit, wherein the output voltage pin of the negative voltage generator is connected to the V-pin of the A / D conversion chip; and the signal output pin of the time base circuit is connected to the clock input pin of the A / D conversion chip.

[0009] In the utility model, the reference voltage source circuit includes: a capacitor C1, a resistor R1, a voltage stabilizing diode D1 and a reference voltage chip.

[0010] Furthermore, the second pin of the reference voltage chip is connected to the cathode of the voltage zener diode D1, and the cathode of the voltage zener diode D1 is also respectively connected to one end of the capacitor C1, one end of the resistor R1, and one end pin of the adjustable potentiometer, and the movable pin of the adjustable potentiometer is connected to the REF pin of the A / D conversion chip; the anode of the voltage zener diode D1 is respectively connected to the first pin of the reference voltage chip, the third pin of the reference voltage chip, the other end of the capacitor C1, and the other end pin of the adjustable potentiometer, and the other end pin of the adjustable potentiometer is connected to the ACOM pin of the A / D conversion chip.

[0011] Among them, a preset value of base-stabilized voltage is provided at the second pin of the reference voltage chip, and the preset value of the base-stabilized voltage is obtained as a reference source of the target value after passing through the adjustable potentiometer, and is input into the A / D conversion chip from the REF pin of the A / D conversion chip.

[0012] In the present invention, the voltage-dividing network with a preset voltage-dividing ratio further includes a capacitor C2; the first resistor includes a resistor R2 and a resistor R3; and the second resistor includes a resistor R4.

[0013] Further, the level signal includes a first level signal and a second level signal; when the analog switch receives the first level signal, only the connection between the first connection end of the analog switch and one end of the resistor R2 is closed, the other end of the resistor R2 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the INLO pin of the A / D conversion chip; when the analog switch receives the second level signal, only the second connection end of the analog switch is closed and connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the INHI pin of the A / D conversion chip; the other end of the resistor R3 and the other end of the resistor R4 are respectively connected to the two ends of the capacitor C2.

[0014] In the present invention, when the input voltage value is greater than a preset threshold value, the first level signal is triggered to be released; when the input voltage value is not greater than the preset threshold value, the second level signal is triggered to be released.

[0015] In order to achieve the above-mentioned object, the utility model further provides an electronic device, which at least comprises any one of the digital voltmeter reference calibration voltage divider circuits described above.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] The utility model proposes a digital voltmeter reference calibration voltage divider circuit and electronic equipment. The design uses a reference voltage source circuit and an adjustable potentiometer to accurately generate and calibrate the reference voltage, thereby improving the measurement accuracy of the digital voltmeter; the use of an adjustable potentiometer allows the user to adjust the reference voltage as needed to adapt to different measurement requirements or calibration conditions; the use of a voltage divider network with a preset voltage divider ratio can provide a stable voltage divider ratio to ensure the accurate distribution of the reference voltage, which is crucial to ensuring the accuracy of the entire measurement system; wherein, by receiving a level signal to control an analog switch, the selection of different resistance mode paths when different degrees of input voltage values ​​can be achieved, which provides the system with flexibility and configurability in voltage divider adjustment. The utility model provides a stable, accurate and easy-to-configure reference calibration voltage divider circuit for a digital voltmeter, which not only improves the accuracy and reliability of the measurement, but also improves the flexibility and cost-effectiveness of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a schematic diagram of a digital voltmeter reference calibration voltage divider circuit in one embodiment of the present invention.

[0019] Figure 2 The circuit structure principle diagram of a voltage divider network with a preset voltage divider ratio in one embodiment of the utility model.

[0020] Figure 3 Another schematic diagram of a digital voltmeter reference calibration voltage divider circuit in an embodiment of the utility model.

[0021] Figure 4 1 is a circuit structure schematic diagram of a negative voltage generator in one embodiment of the utility model.

[0022] Figure 5 The schematic diagram of the circuit structure of the time base circuit in one embodiment of the utility model is shown in FIG.

[0023] Figure 6 The schematic diagram of the circuit structure of the reference voltage source circuit and the adjustable potentiometer in one embodiment of the utility model is shown. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution will be clearly and completely described below in combination with the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] Embodiment 1:

[0026] As attached Figure 1 As shown, in order to solve the above technical problems, the utility model provides a digital voltmeter reference calibration voltage divider circuit, including: an A / D conversion chip; and also including a voltage measurement calibration circuit; the voltage measurement calibration circuit is at least composed of a reference voltage source circuit, an adjustable potentiometer and a voltage divider network with a preset voltage divider ratio; wherein one end of the reference voltage source circuit is connected to one end of the adjustable potentiometer, the other end of the adjustable potentiometer is connected to the A / D conversion chip, and the voltage divider network with a preset voltage divider ratio is connected to the A / D conversion chip.

[0027] It should be noted that the reference calibration voltage divider circuit in the embodiment of the present application can be applied to various digital voltmeters, which usually have multiple ranges, such as 200mV, 2V, 5V, etc. The voltage divider network in this embodiment can adapt to different ranges by changing the resistance ratio or selecting different voltage divider resistors, ensuring that accurate measurement results can be obtained under different ranges.

[0028] Furthermore, voltage meters of different precision have different requirements for reference voltage. The reference voltage source circuit and the adjustable potentiometer in this embodiment can be adjusted to the required precision to meet the measurement requirements of the high-precision voltage meter.

[0029] Digital voltmeters usually use different types of A / D conversion chips, such as ICL7135, ADC0804, etc. The voltage divider circuit in this embodiment can be directly connected to these A / D conversion chips without the need for additional adapter circuits, thereby improving the versatility of the design. Preferably, the A / D conversion chip in this embodiment uses an ICL7135 chip.

[0030] Whether it is laboratory measurement, industrial automation control or consumer electronics, a high-precision reference voltage is required to ensure measurement accuracy and reliability. This application can meet the needs of these different application scenarios and provide a stable reference voltage source. The voltage divider network in this application can adapt the input voltage to the input range of the A / D conversion chip by adjusting the resistance ratio or selecting a suitable voltage divider resistor according to the different input voltages to ensure accurate measurement.

[0031] Preferably, the ratio of the preset voltage divider ratio of the voltage divider network with the preset voltage divider ratio can be 9:1, which means that the voltage will be input at a ratio of one tenth after passing through the voltage divider network to achieve the voltage adjustment purpose of the present application.

[0032] In other embodiments, the reference voltage source circuit can also adapt to different temperature working environments through temperature compensation design to ensure the stability of the reference voltage, thereby ensuring the measurement accuracy of the voltmeter under various temperature conditions.

[0033] As attached Figure 2 As shown, the voltage-dividing network with a preset voltage-dividing ratio at least includes an analog switch, a first resistor and a second resistor; the analog switch is connected to one end of the first resistor or one end of the second resistor according to the level signal received by the analog switch; the other end of the first resistor or the other end of the second resistor is connected to the A / D conversion chip. The voltage-dividing network with a preset voltage-dividing ratio also includes a capacitor C2; the first resistor includes resistors R2 and R3; and the second resistor includes resistor R4.

[0034] It should be noted that by changing the ratio of resistors R2 and R3, different voltage division ratios can be achieved. For example, if the resistance value of resistor R2 is 180k and the resistance value of resistor R3 is 20k, the input voltage will be divided into one-tenth voltage input after passing through the voltage division network. In addition, the resistance value of resistor R4 can be 100k, but it is not limited to this.

[0035] Further, the level signal includes a first level signal and a second level signal; when the analog switch receives the first level signal, only the connection between the first connection end of the analog switch and one end of the resistor R2 is closed, the other end of the resistor R2 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the INLO pin of the A / D conversion chip; when the analog switch receives the second level signal, only the second connection end of the analog switch is closed and connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the INHI pin of the A / D conversion chip; the other end of the resistor R3 and the other end of the resistor R4 are respectively connected to the two ends of the capacitor C2.

[0036] Preferably, the analog switch can be composed of semiconductor devices such as MOSFET or CMOS transistors, which have the characteristics of being turned on and off. When the analog switch receives a high-level signal, the transistor is turned on, and a low-impedance path is formed between its source and drain, so that the first connection end of the analog switch is connected to one end of the resistor R2. When the analog switch receives a low-level signal, the transistor is turned off, and a high-impedance path is formed between the source and the drain, so that the second connection end of the analog switch is connected to one end of the resistor R4.

[0037] Alternatively, the level signal may be a digital logic signal, such as a digital signal from a microcontroller or other logic circuit.

[0038] Preferably, the first level signal is usually a high level, for example, the input voltage value is 5V, when it is sent to the analog switch, the transistor of the analog switch is turned on, and the connection with the resistor R2 is realized. The second level signal is usually a low level, for example, the input voltage value is 1V, when it is sent to the analog switch, the transistor of the analog switch is turned off, and the connection with the resistor R4 is realized.

[0039] Furthermore, when the input voltage value is greater than a preset threshold, the first level signal is triggered to be released; when the input voltage value is not greater than the preset threshold, the second level signal is triggered to be released. Preferably, the preset threshold may be a 2V voltage value, the first level signal may be a high level signal, and the second level signal may be a low level signal, and neither is limited thereto.

[0040] Specifically, the analog switch is used to select the input of the voltage divider network, and the voltage divider formed by resistors R2 and R3 is used to divide the input voltage to different voltage levels. In this embodiment, it can be set as follows: if the external measurement voltage is less than 2V, it will be directly input to resistor R4. This is because when the voltage is lower than 2V, the analog switch will directly flow the current to resistor R4 without passing through the voltage divider network of resistors R2 and R3.

[0041] Preferably, assume that the microcontroller of the digital voltmeter needs to convert a 4V input voltage into a digital signal. The microcontroller first generates a high-level signal and sends it to the analog switch through an appropriate drive circuit. After receiving the high-level signal, the analog switch is turned on and connected to one end of resistor R2, the other end of resistor R2 is connected to one end of resistor R3, and the other end of resistor R3 is connected to the INLO pin of the A / D conversion chip. At this time, the input voltage is divided and input to the INLO pin of the A / D conversion chip.

[0042] Subsequently, the microcontroller generates a low-level signal and sends it to the analog switch through an appropriate drive circuit. After receiving the low-level signal, the analog switch is cut off and connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the INHI pin of the A / D conversion chip. At this time, the input voltage is further divided and input to the INHI pin of the A / D conversion chip.

[0043] In summary, in this embodiment, the microcontroller can be used to control the on and off of the analog switch to achieve switching of voltage division processing when the input voltage has different magnitudes, thereby meeting different measurement requirements.

[0044] In the present utility model, as shown in the attached Figure 3As shown, the voltage measurement calibration circuit also includes: a first driver, a second driver and a display screen. The A / D conversion chip is connected to one end of the first driver and one end of the second driver respectively; the other end of the first driver and the other end of the second driver are connected to the display screen respectively.

[0045] Preferably, the first driver may use a 74HC4511 chip, the second driver may use a ULN2803A chip, and the display screen may use five LED liquid crystal display screens of the same model to display the magnitude of the voltage measurement value, but are not limited thereto.

[0046] Specifically, the 74HC4511 chip is a CMOS eight-bit shift register with high-level effective output, suitable for driving display devices such as light-emitting diodes (LEDs). The function of the first driver is to receive digital signals from the microcontroller and convert these signals into timing signals for driving the LED display. Through the function of the shift register, the first driver can sequentially drive each LED on the LED display to display the magnitude of the voltage measurement value. The first driver also has a latching function, which can ensure that the displayed data will not be lost during the shifting process, thereby ensuring the stability and accuracy of the display.

[0047] The ULN2803A chip is a high-voltage, high-current Darlington transistor array with high input impedance and low output impedance, suitable for driving loads such as motors, relays, and LEDs. The function of the second driver is to amplify the signal output by the first driver so that it can drive the LEDs on the LED display. The second driver also has an overcurrent protection function, which can provide protection when the LED is overloaded to prevent damage to the LED display. Through the drive of the second driver, the LED display can achieve a high-brightness, high-contrast display effect.

[0048] LED LCD displays are usually composed of multiple LEDs, each of which represents a number or symbol. The function of the display is to display the magnitude of the voltage measurement value and provide intuitive visual feedback to the user. Through the combination of LED on and off, the display can show different numbers and symbols to represent the voltage measurement results. Using LED LCD displays of the same model can ensure the consistency and stability of the display, while simplifying circuit design and maintenance.

[0049] In summary, the first driver, the second driver and the display screen work together to achieve accurate display of the voltage measurement value. The first driver is responsible for converting the digital signal into a timing signal, the second driver is responsible for amplifying the signal and driving the LED display screen, and the display screen displays the size of the voltage measurement value through the combination of LED on and off. This design not only improves the accuracy and stability of the display, but also provides an intuitive user interface, allowing users to easily read the voltage measurement results.

[0050] In this embodiment, the voltage measurement calibration circuit further includes: a negative voltage generator and a time base circuit.

[0051] Among them, as attached Figure 4 As shown in the figure, the output voltage pin of the negative voltage generator is connected to the V- pin of the A / D conversion chip; Figure 5 As shown, the signal output pin of the time base circuit is connected to the clock input pin of the A / D conversion chip.

[0052] Preferably, in this embodiment, the negative voltage generator may use a chip of model ICL7660, and the time base circuit may use a time base chip of model 555, but the invention is not limited thereto. The clock input pin of the A / D conversion chip is represented by CLKIN.

[0053] It should be noted that the ICL7660 chip is a negative voltage generator that can convert positive voltage into negative voltage and is usually used to provide negative power for analog circuits. The role of the negative voltage generator is to provide a stable negative voltage reference for the A / D conversion chip, which is essential to ensure the accuracy and linearity of the A / D conversion. By connecting the output voltage pin of the negative voltage generator to the V- pin of the A / D conversion chip, the required negative voltage reference can be provided to the A / D conversion chip, thereby improving the measurement accuracy. The ICL7660 chip has a built-in protection circuit that can provide protection in the event of overvoltage or short circuit, ensuring the safety and stability of the circuit.

[0054] The 555 time base chip is a multi-purpose integrated circuit that can generate a stable square wave, sine wave or other waveform output according to the input signal. The function of the time base circuit is to provide a clock signal for the A / D conversion chip, which is the basis for analog-to-digital conversion. By connecting the signal output pin of the time base circuit to the clock input pin of the A / D conversion chip, it can ensure that the A / D conversion chip samples and converts at a stable clock frequency. The 555 time base chip has a stable oscillation characteristic and can maintain a stable clock frequency under different power supply voltage and temperature conditions, thereby ensuring the accuracy and repeatability of the A / D conversion.

[0055] In summary, the negative voltage generator and the time base circuit jointly provide the necessary voltage reference and clock signal for the A / D conversion chip in this embodiment, thereby ensuring the accuracy and reliability of the digital voltmeter during measurement and conversion. The negative voltage generator provides a stable negative voltage reference, while the time base circuit provides a stable clock signal. The combination of the two enables the A / D conversion to be performed accurately, thereby ensuring the measurement performance and user experience of the digital voltmeter.

[0056] In this embodiment, as shown in the attached Figure 6 As shown, the reference voltage source circuit includes: a capacitor C1, a resistor R1, a voltage stabilizing diode D1 and a reference voltage chip.

[0057] Preferably, the reference voltage chip may be an LM385 chip, the capacitance value of the capacitor C1 may be 10uF, and the resistance value of the resistor R1 may be 4.3k, but they are not limited thereto.

[0058] Furthermore, the second pin of the reference voltage chip is connected to the cathode of the voltage zener diode D1, and the cathode of the voltage zener diode D1 is also respectively connected to one end of the capacitor C1, one end of the resistor R1, and one end pin of the adjustable potentiometer, and the movable pin of the adjustable potentiometer is connected to the REF pin of the A / D conversion chip; the anode of the voltage zener diode D1 is respectively connected to the first pin of the reference voltage chip, the third pin of the reference voltage chip, the other end of the capacitor C1, and the other end pin of the adjustable potentiometer, and the other end pin of the adjustable potentiometer is connected to the ACOM pin of the A / D conversion chip.

[0059] Among them, a preset value of base-stabilized voltage is provided at the second pin of the reference voltage chip, and the preset value of the base-stabilized voltage is obtained as a reference source of the target value after passing through the adjustable potentiometer, and is input into the A / D conversion chip from the REF pin of the A / D conversion chip.

[0060] It should be noted that, in this embodiment, the adjustable potentiometer can be a variable resistor, whose moving piece pin is connected to the REF pin of the A / D conversion chip, and the other end pin is connected to the ACOM pin of the A / D conversion chip. The function of the adjustable potentiometer is to adjust the magnitude of the reference voltage by changing its resistance value. When the moving piece of the adjustable potentiometer moves, the resistance ratio between it and the fixed resistor changes, thereby changing the magnitude of the reference voltage. In this way, the user can easily adjust the reference voltage to adapt to different measurement requirements or calibration conditions.

[0061] In addition, the reference voltage chip provides a preset base stabilizing voltage, which is usually a stable voltage close to 1.000V. Preferably, in this embodiment, the preset base stabilizing voltage can be 1.24V, and after adjustment by the adjustable potentiometer, an accurate reference source voltage of the target value of 1V is obtained, which is not limited to this. The function of the voltage stabilizing diode D1 is to protect the reference voltage chip from overvoltage damage, and also provide a certain voltage stability and temperature stability for the circuit. The function of the capacitor C1 may be to filter out noise or prevent high-frequency interference, thereby improving the quality of the reference voltage.

[0062] The reference voltage source circuit provides a stable reference voltage, which is the basis for accurate measurement. The adjustable potentiometer allows the user to flexibly adjust the reference voltage to adapt to different application scenarios and measurement requirements. Through the combination of the reference voltage source circuit and the adjustable potentiometer, the present embodiment provides an accurate, flexible and easy-to-adjust reference voltage source, thereby improving the measurement accuracy and user-friendliness of the digital voltmeter.

[0063] In other embodiments, the digital voltmeter needs to be calibrated regularly to ensure its accuracy and reliability. The present application can also design a 6 1 / 2-digit multimeter as a monitoring meter for monitoring and adjusting the reference voltage. The multimeter itself is an accurate measuring tool, and using it to adjust the reference voltage can ensure the accuracy and reliability of the adjustment process. By using an adjustable potentiometer, the user can easily adjust the reference voltage until the reading displayed by the multimeter matches the expected 1.000V. This manual adjustment method is intuitive and easy to operate, and does not require complex circuit debugging. The multimeter usually has a clear digital display, and the user can intuitively see the changes in the reference voltage and adjust it accordingly. This display method makes the adjustment process more intuitive and easy to understand.

[0064] In some complex designs, it may be necessary to use external test equipment (such as a standard voltage source) to adjust the reference voltage. However, this application simplifies the adjustment process by using a multimeter without the need for additional external equipment.

[0065] Moreover, the calibration steps of the present application are simple and clear. The user only needs to connect the probe of the multimeter to the output end of the adjustable potentiometer, and then rotate the potentiometer knob until the voltage value displayed by the multimeter is close to 1.000 V. This simple and easy-to-understand calibration step reduces the difficulty of user operation.

[0066] In summary, this embodiment uses a 6 1 / 2 multimeter as a monitoring meter, an adjustable potentiometer for manual adjustment, an intuitive digital display, and easy-to-understand adjustment steps, which demonstrates its convenience and user-friendliness in adjustment. This design allows users to easily adjust the reference voltage, thereby ensuring the accuracy and reliability of the digital voltmeter.

[0067] Embodiment 2:

[0068] In order to solve the above technical problems, the utility model also proposes an electronic device, which at least includes any one of the digital voltmeter reference calibration voltage divider circuits described above.

[0069] Preferably, the electronic device in this embodiment can be a smart voltmeter, which is used for industrial automation control, laboratory measurement or household electrical safety detection. The user can adjust the reference voltage through simple operations to ensure the accuracy of the measurement results. At the same time, the smart voltmeter can be connected to a computer or other device, and remote monitoring and data processing can be performed through software to further improve the efficiency of measurement and analysis. The specific implementation process is as follows:

[0070] Firstly, according to the requirements of the digital voltmeter, a reference calibration voltage divider circuit is designed and implemented. The circuit includes an A / D conversion chip, a voltage measurement calibration circuit, a negative voltage generator, a time base circuit and a reference voltage source circuit.

[0071] Component selection: Select appropriate components, such as using a first driver of model 74HC4511, a second driver of model ULN2803A, a negative voltage generator of model ICL7660, a timing chip of model 555, and a reference voltage chip of model LM385.

[0072] Circuit assembly: Assemble the selected components into circuit boards according to design requirements, and perform soldering and debugging.

[0073] In the voltmeter, the operation of the first driver, the second driver and the adjustable potentiometer can be controlled to achieve adjustment and display of the reference voltage.

[0074] In summary, this embodiment improves the measurement accuracy of electronic equipment through accurate reference voltage generation and flexible voltage divider network control. The design of the adjustable potentiometer allows users to easily adjust the reference voltage and calibrate without professional knowledge. The electronic equipment can be applied to various voltage input ranges to ensure the accuracy and reliability of the measurement results. The addition of the negative voltage generator and the time base circuit provides a stable working environment for the A / D conversion chip and reduces the influence of external interference on the measurement results.

[0075] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0076] The embodiments of the utility model are described above in conjunction with the accompanying drawings, but the utility model is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the utility model, ordinary technicians in this field can also make many forms without departing from the scope of protection of the utility model and the claims, all of which are within the protection of the utility model.

Claims

1. A digital voltmeter reference calibration voltage divider circuit, comprising: A / D conversion chip; characterized in that, It also includes a voltage measurement calibration circuit; the voltage measurement calibration circuit is composed of at least a reference voltage source circuit, an adjustable potentiometer and a voltage divider network with a preset voltage divider ratio; wherein one end of the reference voltage source circuit is connected to one end of the adjustable potentiometer, the other end of the adjustable potentiometer is connected to the A / D conversion chip, and the voltage divider network with a preset voltage divider ratio is connected to the A / D conversion chip; Among them, the voltage divider network with a preset voltage divider ratio includes at least an analog switch, a first resistor and a second resistor; the analog switch is connected to one end of the first resistor or one end of the second resistor according to the level signal it receives; the other end of the first resistor or the other end of the second resistor is connected to the A / D conversion chip.

2. A digital voltmeter reference calibration voltage divider circuit according to claim 1, characterized in that: The voltage measurement calibration circuit also includes: a first driver, a second driver and a display screen; The A / D conversion chip is connected to one end of the first driver and one end of the second driver respectively; the other end of the first driver and the other end of the second driver are connected to the display screen respectively.

3. A digital voltmeter reference calibration voltage divider circuit according to claim 2, characterized in that: The voltage measurement calibration circuit also includes: a negative voltage generator and a time base circuit; The output voltage pin of the negative voltage generator is connected to the V-pin of the A / D conversion chip; and the signal output pin of the time base circuit is connected to the clock input pin of the A / D conversion chip.

4. A digital voltmeter reference calibration voltage divider circuit according to claim 3, characterized in that: The reference voltage source circuit includes: a capacitor C1, a resistor R1, a voltage stabilizing diode D1 and a reference voltage chip.

5. A digital voltmeter reference calibration voltage divider circuit according to claim 4, characterized in that: The second pin of the reference voltage chip is connected to the cathode of the voltage zener diode D1, and the cathode of the voltage zener diode D1 is also connected to one end of the capacitor C1, one end of the resistor R1, and one end pin of the adjustable potentiometer, and the movable pin of the adjustable potentiometer is connected to the REF pin of the A / D conversion chip; The positive electrode of the voltage zener diode D1 is respectively connected to the first pin of the reference voltage chip, the third pin of the reference voltage chip, the other end of the capacitor C1, and the other end pin of the adjustable potentiometer, and the other end pin of the adjustable potentiometer is connected to the ACOM pin of the A / D conversion chip; Among them, a preset value of base-stabilized voltage is provided at the second pin of the reference voltage chip, and the preset value of the base-stabilized voltage is obtained as a reference source of the target value after passing through the adjustable potentiometer, and is input into the A / D conversion chip from the REF pin of the A / D conversion chip.

6. A digital voltmeter reference calibration voltage divider circuit according to claim 5, characterized in that: The voltage-dividing network with a preset voltage-dividing ratio further includes a capacitor C2; the first resistor includes a resistor R2 and a resistor R3; and the second resistor includes a resistor R4.

7. A digital voltmeter reference calibration voltage divider circuit according to claim 6, characterized in that: The level signal includes a first level signal and a second level signal; When the analog switch receives the first level signal, only the connection between the first connection end of the analog switch and one end of the resistor R2 is closed, the other end of the resistor R2 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the INLO pin of the A / D conversion chip; When the analog switch receives the second level signal, only the second connection end of the analog switch is closed and connected to one end of the resistor R4, and the other end of the resistor R4 is connected to the INHI pin of the A / D conversion chip; The other ends of the resistor R3 and the other ends of the resistor R4 are connected to both ends of the capacitor C2 respectively.

8. A digital voltmeter reference calibration voltage divider circuit according to claim 7, characterized in that: When the input voltage value is greater than a preset threshold, triggering the release of the first level signal; When the input voltage value is not greater than the preset threshold, the second level signal is triggered to be released.

9. An electronic device, characterized in that: The electronic device at least comprises the digital voltmeter reference calibration voltage divider circuit as described in any one of claims 1 to 8.

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