High-precision voltage sampling circuit

Abstract

The utility model discloses a high-precision voltage sampling circuit, which comprises an input module, a voltage processing module, a micro-processing module and a reference voltage module, the input module, the voltage processing module and the micro-processing module are electrically connected in sequence; the reference voltage module is electrically connected with the micro-processing module and is used for providing reference voltage for the micro-processing module; the voltage processing module is used for carrying out voltage division, filtering and operational amplification processing on the input voltage; wherein the reference voltage module comprises a reference voltage chip; the precision of the reference voltage chip is + / -0.1%; the voltage processing module comprises a voltage dividing unit, and the resistance precision of the voltage dividing unit is + / -0.1%. By adopting the high-precision divider resistor and the LM4040-N reference voltage chip and utilizing the characteristics of high precision, low temperature drift and low noise of the LM4040-N reference voltage chip, the reference voltage precision is improved, the total error of the system is reduced, and the problems that a voltage sampling circuit is large in sampling error, poor in environmental adaptability and unstable in ADC conversion result are solved.

Description

Technical Field

[0001] This utility model relates to the technical field of voltage sampling circuits, and in particular to a high-precision voltage sampling circuit. Background Technology

[0002] Voltage sampling circuits are used to monitor the power supply voltage in electronic systems: Real-time monitoring of the power supply output voltage allows the system to understand whether the power supply is operating normally and whether the output voltage is within the specified range. For example, in computer power supplies, voltage sampling circuits monitor the output voltage of each circuit; when abnormal voltage fluctuations occur, protective measures can be taken in time to prevent hardware damage due to overvoltage or undervoltage. Voltage sampling circuits can also be used to implement closed-loop control: in a feedback control system, the output voltage is sampled and fed back to the input terminal, compared with the set value, and the controller adjusts the output based on the difference to stabilize the system output voltage near the set value. In switching power supplies, closed-loop control using voltage sampling circuits ensures that the output voltage remains stable despite changes in input voltage or load.

[0003] In addition to its primary function, voltage sampling circuits can also be used to measure voltage values ​​and protect circuit safety. They provide a signal proportional to the voltage being measured to the measuring instrument for accurate voltage measurement. For example, in a digital multimeter, the voltage sampling circuit converts the high voltage being measured into a low voltage signal suitable for internal circuit processing, which is then converted by an A / D converter and calculated to display the actual voltage value. When an abnormal voltage is detected, such as overvoltage, undervoltage, or reverse voltage, the protection circuit is triggered, cutting off the power supply or taking other protective measures to protect the components in the circuit from damage caused by overvoltage or undervoltage. For instance, in a mobile phone charger, when an excessively high input voltage is detected, the voltage sampling circuit triggers a protection mechanism to prevent damage to the phone battery and other circuits due to overvoltage.

[0004] However, existing voltage sampling circuits suffer from problems such as large sampling errors, poor environmental adaptability, and unstable ADC conversion results. Utility Model Content

[0005] Existing voltage sampling circuits suffer from large sampling errors, poor environmental adaptability, and unstable ADC conversion results.

[0006] To address the aforementioned issues, a high-precision voltage sampling circuit is proposed. By employing high-precision voltage divider resistors and an LM4040-N reference voltage chip, and leveraging the high precision, low temperature drift, and low noise characteristics of the LM4040-N reference voltage chip, the accuracy of the reference voltage is improved, the total system error is reduced, and the problems of large sampling error, poor environmental adaptability, and unstable ADC conversion results in voltage sampling circuits are solved.

[0007] A high-precision voltage sampling circuit includes:

[0008] Input module;

[0009] Voltage processing module;

[0010] Microprocessor module;

[0011] Reference voltage module;

[0012] The input module, voltage processing module, and microprocessor module are electrically connected in sequence.

[0013] The reference voltage module is electrically connected to the microprocessor module and is used to provide a reference voltage to the microprocessor module;

[0014] The voltage processing module is used to perform voltage division, filtering, and operational amplifier processing on the input voltage;

[0015] The reference voltage module includes a reference voltage chip; the accuracy of the reference voltage chip is ±0.1%.

[0016] The voltage processing module includes a voltage divider unit, and the resistance accuracy of the voltage divider unit is ±0.1%.

[0017] In conjunction with the high-precision voltage sampling circuit described in this utility model, in a first possible embodiment, the voltage processing module further includes:

[0018] RC filter unit and operational amplifier unit;

[0019] The output terminal of the voltage divider unit is electrically connected to the input terminal of the RC filter unit;

[0020] The output terminal of the RC filter unit is electrically connected to the input terminal of the operational amplifier unit;

[0021] The output terminal of the operational amplifier unit is electrically connected to the microprocessor module.

[0022] In conjunction with the first possible embodiment of this utility model, in the second possible embodiment, the voltage divider unit includes:

[0023] First resistor and second resistor;

[0024] The first end of the first resistor is electrically connected to the input module, and the second end of the first resistor is electrically connected to the RC filter unit and the first end of the second resistor.

[0025] The second terminal of the second resistor is grounded.

[0026] In conjunction with the second possible implementation of this utility model, in the third possible implementation, the first resistor and the second resistor are metal film resistors with an accuracy of ±0.1%.

[0027] In conjunction with the second possible embodiment of this utility model, and in the fourth possible embodiment, the RC filter unit includes:

[0028] The third resistor and the first capacitor;

[0029] The third resistor is electrically connected to the second end of the first resistor and the first end of the second resistor;

[0030] The second end of the third resistor is electrically connected to the first end of the first capacitor and the operational amplifier unit;

[0031] The second terminal of the first capacitor is grounded.

[0032] In conjunction with the fourth possible implementation of this utility model, and in the fifth possible implementation, the operational amplifier unit includes an operational amplifier;

[0033] The operational amplifier includes a positive input terminal, a negative input terminal, a power supply terminal, a ground terminal, and an output terminal;

[0034] The positive input terminal is electrically connected to the second terminal of the third resistor and the first terminal of the first capacitor;

[0035] The negative input terminal is short-circuited with the output terminal;

[0036] The power supply terminal is electrically connected to the input power supply of the operational amplifier to obtain the voltage, and the ground terminal is grounded;

[0037] The output terminal is electrically connected to the microprocessor module.

[0038] In conjunction with the high-precision voltage sampling circuit described in this utility model, in a sixth possible embodiment, the reference voltage module further includes:

[0039] Fourth resistor;

[0040] The first end of the fourth resistor is electrically connected to the input power supply of the reference voltage chip, the second end is electrically connected to the positive pin of the reference voltage chip, the negative pin of the reference voltage chip is grounded, and the output end of the reference voltage chip is electrically connected to the reference voltage pin of the microprocessor module.

[0041] In conjunction with the sixth and seventh possible embodiments of this utility model, the reference voltage chip is an LM4040-N.

[0042] The high-precision voltage sampling circuit described in this utility model improves the reference voltage accuracy and reduces the total system error by using high-precision voltage divider resistors and an LM4040-N reference voltage chip. This solves the problems of large sampling error, poor environmental adaptability, and unstable ADC conversion results in voltage sampling circuits. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a module structure diagram of a high-precision voltage sampling circuit according to the present invention;

[0045] Figure 2 This is a circuit structure diagram of a high-precision voltage sampling circuit according to the present invention;

[0046] Components and their serial numbers:

[0047] 100 – Input module, 200 – Voltage processing module, 210 – Voltage divider unit, 220 – RC filter unit, 230 – Operational amplifier unit, 300 – Microprocessor module, 400 – Reference voltage module. Detailed Implementation

[0048] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of this utility model.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0050] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0051] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0053] Existing voltage sampling circuits suffer from large sampling errors, poor environmental adaptability, and unstable ADC conversion results.

[0054] To address the above problems, a high-precision voltage sampling circuit is proposed.

[0055] A high-precision voltage sampling circuit, such as Figure 1 , Figure 1 This is a module structure diagram of a high-precision voltage sampling circuit according to the present invention, including an input module 100, a voltage processing module 200, a microprocessor module 300, and a reference voltage module 400; the input module 100, voltage processing module 200, and microprocessor module 300 are electrically connected in sequence; the reference voltage module 400 is electrically connected to the microprocessor module 300 and is used to provide a reference voltage to the microprocessor module 300; the voltage processing module 200 is used to perform voltage division, filtering, and operational amplifier processing on the input voltage; wherein, the reference voltage module 400 includes a reference voltage chip U2; the accuracy of the reference voltage chip U2 is ±0.1%; the voltage processing module 200 includes a voltage divider unit 210, and the resistor accuracy of the voltage divider unit 210 is ±0.1%. By employing high-precision voltage divider resistors and the LM4040-N reference voltage chip U2, and leveraging the high precision, low temperature drift, and low noise characteristics of the LM4040-N reference voltage chip U2, the accuracy of the reference voltage is improved, the total system error is reduced, and the problems of large sampling error, poor environmental adaptability, and unstable ADC conversion results in voltage sampling circuits are solved.

[0056] In this embodiment, the input module 100 inputs a 0-10V voltage, the voltage processing module 200 adapts the input voltage to the ADC range, the microprocessor module 300 is configured with an ADC unit to perform ADC calculations, and the reference voltage module 400 uses an LM4040-N to provide a stable reference voltage (such as 2.048V, 2.5V, or 5V) and is connected to the reference voltage input terminal of the ADC of the microprocessor module 300; the microprocessor module 300 uses the output of the LM4040-N as the reference voltage; it processes the ADC data to achieve calibration and output.

[0057] The LM4040-N series precision voltage reference power supply chip in this embodiment has advantages such as high initial accuracy (±0.1%), low temperature drift (20~50ppm / ℃), and low noise (35μVpp).

[0058] like Figure 2 , Figure 2 The circuit diagram shows a high-precision voltage sampling circuit of this utility model. The voltage processing module 200 also includes an RC filter unit 220 and an operational amplifier unit 230. The output terminal of the voltage divider unit 210 is electrically connected to the input terminal of the RC filter unit 220. The output terminal of the RC filter unit 220 is electrically connected to the input terminal of the operational amplifier unit 230. The output terminal of the operational amplifier unit 230 is electrically connected to the microprocessor module 300.

[0059] Specifically, the voltage divider unit 210 includes a first resistor R1 and a second resistor R2; the first end of the first resistor R1 is electrically connected to the input module 100, the second end of the first resistor R1 is electrically connected to the RC filter unit 220 and the first end of the second resistor R2; the second end of the second resistor R2 is grounded.

[0060] Preferably, the first resistor R1 and the second resistor R2 are metal film resistors with an accuracy of ±0.1%. Using high-precision metal film resistors (±0.1%), the chip of the microprocessor module 300 performs temperature compensation on the first resistor R1 and the second resistor R2 through a temperature compensation design.

[0061] Specifically, the RC filter unit 220 includes a third resistor R3 and a first capacitor C; the third resistor R3 is electrically connected to the second end of the first resistor R1 and the first end of the second resistor R2; the second end of the third resistor R3 is electrically connected to the first end of the first capacitor C and the operational amplifier unit 230; the second end of the first capacitor C is grounded.

[0062] In this embodiment, the RC filter unit 220 is used to perform low-pass filtering to suppress high-frequency noise.

[0063] Specifically, the operational amplifier unit 230 includes an operational amplifier U2A; the operational amplifier U2A includes a positive input terminal (+), a negative input terminal (-), a power supply terminal (3.3V), a ground terminal (GND), and an output terminal; the positive input terminal is electrically connected to the second end of the third resistor R3 and the first end of the first capacitor C; the negative input terminal is shorted to the output terminal; the power supply terminal is electrically connected to the input power supply of the operational amplifier U2A to obtain the voltage, and the ground terminal is grounded; the output terminal is electrically connected to the microprocessor module 300.

[0064] Furthermore, the reference voltage module 400 also includes a fourth resistor R4; the first end of the fourth resistor R4 is electrically connected to the input power supply (3.3V) of the reference voltage chip U2, the second end is electrically connected to the positive pin of the reference voltage chip U2, the negative terminal of the reference voltage chip U2 is grounded, and the output terminal of the reference voltage chip U2 is electrically connected to the reference voltage pin ADCVREF of the microprocessor module 300.

[0065] In this embodiment, the Vref pin (ADCVREF) of the microprocessor's built-in ADC is connected to the output pin (NC) of the reference voltage chip U2 (LM4040-N). Utilizing the high precision, low temperature drift, and low noise characteristics of the LM4040-N reference voltage chip U2, the reference voltage accuracy can be improved to ±0.1%, and the total system error can be reduced by more than 50%. Through filtering design, it can adapt to complex industrial environments, and its cost is lower than traditional high-precision reference source solutions (such as LTZ1000).

[0066] Preferably, the reference voltage chip U2 is an LM4040-N.

[0067] In this embodiment, the input voltage of the input module 100 is 0-10V. The voltage divider resistors R1 and R2 (accuracy ±0.1%) in the voltage divider unit 210 scale the input voltage to 0-1.998V. The RC filter unit has R = 1kΩ and C = 100nF to filter out high-frequency interference. The operational amplifier U2A (preferably OPA2188) in the operational amplifier unit 230 forms a voltage follower to improve driving capability. The reference voltage chip U2 (LM4040-N) outputs 2.048V to the Vref reference terminal (ADCVREF) of the built-in ADC unit of the microprocessor module. The LM4040-N series precision voltage reference power supply chip, with its high initial accuracy (±0.1%), low temperature drift (20-50ppm / ℃), and low noise (35μVpp), solves the problem of unstable reference voltage in the prior art.

[0068] In practical implementation, the hardware configuration includes an input voltage range of 0–10V, which is divided to 0–1.998V by R1 = 14.3kΩ and R2 = 3.57kΩ; an RC filter unit (R = 1kΩ, C = 100nF); an operational amplifier OPA2188 forming a voltage follower; an LM4040-N providing a 2.048V ± 0.1% reference voltage; and a microprocessor module with a built-in ADC unit to process ADC data and perform calibration and output.

[0069] Upon power-up, a known standard voltage (e.g., 10V) is acquired, and the voltage divider ratio error is calculated. The calibration coefficient is stored in the EEPROM, and the sampled value is corrected in real time. Performance specifications: Sampling error < ±0.1% over the entire temperature range (-40~85℃); peak-to-peak noise < 1mV.

[0070] The high-precision voltage sampling circuit of this invention employs high-precision voltage divider resistors and a high-precision LM4040-N reference voltage chip U2, achieving a resistor accuracy as low as ±0.1% and a reference voltage accuracy as low as ±0.1%. Utilizing the high performance of the LM4040-N series precision voltage reference power supply chip (high initial accuracy (±0.1%), low temperature drift (20~50ppm / ℃), and low noise (35μVpp), this invention solves the problem of unstable reference voltage in existing technologies, improves reference voltage accuracy, reduces the total system error, and resolves the issues of large sampling error, poor environmental adaptability, and unstable ADC conversion results in voltage sampling circuits.

[0071] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A high-precision voltage sampling circuit, characterized in that it comprises: Input module; Voltage processing module; Microprocessor module; Reference voltage module; The input module, voltage processing module, and microprocessor module are electrically connected in sequence. The reference voltage module is electrically connected to the microprocessor module and is used to provide a reference voltage to the microprocessor module; The voltage processing module is used to perform voltage division, filtering, and operational amplifier processing on the input voltage; The reference voltage module includes a reference voltage chip; the accuracy of the reference voltage chip is ±0.1%. The voltage processing module includes a voltage divider unit, and the resistance accuracy of the voltage divider unit is ±0.1%. The reference voltage chip is LM4040-N; The temperature drift of the reference voltage chip is 20~50 ppm / °C; The noise generated by the reference voltage chip is 35μVpp.

2. The high-precision voltage sampling circuit according to claim 1, characterized in that, The voltage processing module further includes: RC filter unit and operational amplifier unit; The output terminal of the voltage divider unit is electrically connected to the input terminal of the RC filter unit; The output terminal of the RC filter unit is electrically connected to the input terminal of the operational amplifier unit; The output terminal of the operational amplifier unit is electrically connected to the microprocessor module.

3. The high-precision voltage sampling circuit according to claim 2, characterized in that, The voltage divider unit includes: First resistor and second resistor; The first end of the first resistor is electrically connected to the input module, and the second end of the first resistor is electrically connected to the RC filter unit and the first end of the second resistor. The second terminal of the second resistor is grounded.

4. The high-precision voltage sampling circuit according to claim 3, characterized in that, The first resistor and the second resistor are metal film resistors with an accuracy of ±0.1%.

5. The high-precision voltage sampling circuit according to claim 3, characterized in that, The RC filter unit includes: The third resistor and the first capacitor; The third resistor is electrically connected to the second end of the first resistor and the first end of the second resistor; The second end of the third resistor is electrically connected to the first end of the first capacitor and the operational amplifier unit; The second terminal of the first capacitor is grounded.

6. The high-precision voltage sampling circuit according to claim 5, characterized in that, The operational amplifier unit includes an operational amplifier; The operational amplifier includes a positive input terminal, a negative input terminal, a power supply terminal, a ground terminal, and an output terminal; The positive input terminal is electrically connected to the second terminal of the third resistor and the first terminal of the first capacitor; The negative input terminal is short-circuited with the output terminal; The power supply terminal is electrically connected to the input power supply of the operational amplifier to obtain the voltage, and the ground terminal is grounded; The output terminal is electrically connected to the microprocessor module.

7. The high-precision voltage sampling circuit according to claim 1, characterized in that, The reference voltage module also includes: Fourth resistor; The first end of the fourth resistor is electrically connected to the input power supply of the reference voltage chip, the second end is electrically connected to the positive pin of the reference voltage chip, the negative pin of the reference voltage chip is grounded, and the output end of the reference voltage chip is electrically connected to the reference voltage pin of the microprocessor module.

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