Wide range voltage sampling and protection circuit

Abstract

This invention discloses a wide-range voltage sampling and protection circuit, comprising: a modular bridge arm circuit, a sampling node, and a bidirectional clamping protection circuit; the modular bridge arm circuit is based on a three-bridge arm structure, connected to the sampling node, and can be expanded to form a multi-bridge arm structure with four, five, or more bridge arms; the sampling node is connected to the bidirectional clamping protection circuit; the bidirectional clamping protection circuit clamps the sampled voltage within the range of 0V to the supply voltage. This invention can linearly and synchronously adjust the voltage divider switching inflection point and the lowest measurable negative voltage by adjusting the reference voltage. The circuit automatically switches the number of bridge arms participating in the voltage divider according to the sampled voltage, realizing multi-level passive adaptive voltage divider; the circuit adopts a completely passive design, requiring no active components or additional power supply, and features high precision, wide range, and hardware pin protection, effectively solving the problems of narrow range, incompatibility with negative voltage, and difficulty in balancing accuracy and range in ADC acquisition circuits.

Description

Technical Field

[0001] This invention belongs to the field of analog signal acquisition technology, specifically relating to a wide-range voltage sampling and protection circuit. Background Technology

[0002] Voltage sampling technology is widely used in industrial control, power monitoring, and high-precision analog signal acquisition. However, existing resistance sampling network technology has many technical defects: traditional acquisition circuits only support fixed voltage division and cannot balance wide range and low voltage range acquisition accuracy; negative voltage acquisition relies on active devices such as operational amplifiers, resulting in complex circuit structures, high costs, the need for additional power supply, and easy introduction of circuit noise; the functional division of bridge arms in conventional segmented acquisition circuits is vague, making it impossible to achieve precise range switching control; at the same time, existing circuits have poor range scalability and lack highly reliable passive hardware protection mechanisms. Over-range voltage and negative voltage signals can easily damage the ADC chip, making it difficult to meet the high-precision, wide-range, and high-reliability acquisition requirements of industrial scenarios. Summary of the Invention

[0003] This invention aims to address the shortcomings of existing technologies and provides the following solutions: A wide-range voltage sampling and protection circuit includes: a modular bridge arm circuit, a sampling node, and a bidirectional clamping protection circuit; The modular bridge arm circuit is based on a three-bridge arm structure, which connects to the sampling node and can be expanded to form a multi-bridge arm structure with four, five, or more bridge arms. The sampling node is connected to the bidirectional clamping protection circuit; The bidirectional clamping protection circuit clamps the sampled voltage within the range of 0V to the supply voltage.

[0004] Preferably, the three-arm basic structure includes: an input arm, a unidirectional reference arm, and a bidirectional reference arm; The input bridge arm is connected to the sampling node via the input signal terminal and the first current-limiting resistor, and is used to receive the voltage signal to be collected. The bidirectional reference bridge arm is directly connected to the sampling node via the first reference voltage terminal and the third current-limiting resistor, which is used to realize bidirectional conduction of the level and basic voltage division. The unidirectional reference bridge arm is connected to the sampling node via a second reference voltage terminal, a unidirectional conduction element, and a second current-limiting resistor, in sequence, to realize unidirectional power supply, signal level boosting, anti-backflow control, and automatic switching of voltage divider levels.

[0005] Preferably, in the multi-arm structure formed by extending the three-arm basic structure, the newly added arms are all unidirectional reference arms, and each extended unidirectional reference arm is independently equipped with a reference voltage, a unidirectional conducting element and a current limiting resistor.

[0006] Preferably, when the circuit is in the fully conducting state of the voltage divider, the input voltage... With sampling node voltage The relationship is: in, This represents the first current-limiting resistor. This indicates the third current-limiting resistor. Indicates the first reference voltage terminal. n Indicates the total number of bridge arms. Represented as the first i Reference voltage of the reference bridge arm. Indicates the first i The current-limiting resistor of the bridge arm, Indicates the first i The forward voltage drop of the diode in the unidirectional reference bridge arm.

[0007] Preferably, the unidirectional conducting element is a diode, and the anode of the unidirectional conducting element is connected to the reference voltage terminal of the corresponding unidirectional reference bridge arm, and the cathode is connected to the corresponding current limiting resistor; The unidirectional reference bridge arm is activated only when the voltage at the sampling node is less than the corresponding reference voltage, and participates in parallel voltage division. When the sampling node voltage is greater than or equal to the corresponding reference voltage, it is turned off, and the unidirectional reference bridge arm exits the voltage divider. At this time, the input voltage... With sampling node voltage The relationship is: .

[0008] Preferably, the bidirectional reference bridge arm does not have unidirectional conducting elements, and there is bidirectional conduction between the reference voltage and the sampling node, which participates in the circuit voltage division throughout the process to maintain the sampling voltage level reference.

[0009] Preferably, the voltage divider inflection point, the lowest measurable negative voltage, and the reference voltage of the circuit satisfy the following: Voltage divider inflection point input voltage: in, This indicates the input voltage at the voltage divider inflection point. Indicates the second reference voltage terminal; Minimum measurable negative pressure: in, This indicates the lowest measurable negative pressure.

[0010] Preferably, the three-bridge arm foundation structure realizes two-stage adaptive voltage switching; Based on this, the four-arm structure realizes three-stage adaptive voltage division switching, and the five-arm structure realizes four-stage adaptive voltage division switching. The voltage division range expands synchronously with the increase of the number of unidirectional reference arms. In the multi-arm structure, the first k The input voltage at each voltage divider inflection point satisfies: in, Indicates the first k Input voltage at the voltage divider inflection point k This indicates the number of unidirectional reference arms that have been turned off. Indicates the first k +1 reference voltage.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention allows for linear and synchronous adjustment of the voltage divider switching inflection point and the lowest measurable negative voltage by adjusting the reference voltage. The circuit automatically switches the number of bridge arms participating in the voltage divider based on the sampled voltage, achieving multi-level passive adaptive voltage divider and compatibility with ultra-wide range of positive and negative voltage acquisition. The circuit adopts a completely passive design, requiring no active components or additional power supply, and features high precision, wide range, and hardware pin protection. It effectively solves the problems of narrow range, incompatibility with negative voltage, and difficulty in balancing accuracy and range in ADC chip acquisition circuits, and is suitable for various embedded scenarios such as industrial testing, voltage monitoring, and sensor signal acquisition. Attached Figure Description

[0012] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the circuit structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the multi-arm extension structure according to an embodiment of the present invention; Figure 3 The input voltage of this embodiment of the invention With sampling voltage Piecewise characteristic curves. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Example 1 In this embodiment, as Figure 1 As shown, a wide-range voltage sampling and protection circuit includes: a modular bridge arm circuit, a sampling node, and a bidirectional clamping protection circuit.

[0017] The modular bridge arm circuit is based on a three-bridge arm structure, connecting to sampling nodes, and can be expanded to form multi-bridge arm structures with four, five, or more arms. The sampling nodes are connected to a bidirectional clamping protection circuit. This circuit clamps the sampled voltage within the range of 0V to the supply voltage.

[0018] The three-bridge arm basic structure includes: an input bridge arm, a unidirectional reference bridge arm, and a bidirectional reference bridge arm. The input bridge arm is connected to the sampling node via a first current-limiting resistor from the input signal terminal, used to receive the voltage signal to be acquired. The core of the input bridge arm is to receive a wide range of positive and negative voltage signals to be acquired. It is directly connected to the sampling node after the first current-limiting resistor is connected in series from the input signal terminal, achieving current limiting and transmission of the input signal. The bidirectional reference bridge arm is directly connected to the sampling node via a third current-limiting resistor from the first reference voltage terminal, used to achieve bidirectional conduction and basic voltage division. The bidirectional reference bridge arm does not have unidirectional conduction components, allowing voltage to flow bidirectionally and participating in voltage division throughout the process, providing a stable voltage reference for the circuit. This ensures that negative voltage signals can be converted to the voltage range that the ADC can acquire, making it an essential fixed bridge arm in the three-bridge arm basic structure. The unidirectional reference bridge arm is connected to the sampling node sequentially from the second reference voltage terminal via a unidirectional conducting element and a second current-limiting resistor. It is used to achieve unidirectional power supply, signal level boosting, backflow prevention control, and automatic switching of voltage divider levels. The unidirectional reference bridge arm is equipped with a unidirectional conducting element to achieve unidirectional conduction control, automatically determining whether to participate in voltage division based on the sampling node voltage, thus completing the voltage divider level switching. In the multi-bridge arm structure formed by expanding the three-bridge arm basic structure, all newly added bridge arms are unidirectional reference bridge arms, and each expanded unidirectional reference bridge arm independently has a reference voltage, a unidirectional conducting element, and a current-limiting resistor.

[0019] When the circuit is in the fully conducting state of the voltage divider, the input voltage With sampling node voltage The relationship is: in, This represents the first current-limiting resistor. This indicates the third current-limiting resistor. Indicates the first reference voltage terminal. n Indicates the total number of bridge arms. Represented as the first i Reference voltage of the reference bridge arm. Indicates the first i The current-limiting resistor of the bridge arm, Indicates the first i The forward voltage drop of the diode in the unidirectional reference bridge arm.

[0020] The unidirectional conducting element is a diode. The anode of the unidirectional conducting element is connected to the reference voltage terminal of the corresponding unidirectional reference bridge arm, and the cathode is connected to the corresponding current-limiting resistor. It conducts only when the sampling node voltage is less than the corresponding reference voltage, and the unidirectional reference bridge arm participates in parallel voltage division. When the sampling node voltage is greater than or equal to the corresponding reference voltage, it turns off, and the unidirectional reference bridge arm exits the voltage division. At this time, the term corresponding to this bridge arm in the above formula... Remove from the numerator, the corresponding value in the denominator. Also removed simultaneously, input voltage With sampling node voltage The relationship is: .

[0021] The reference voltage values ​​of each unidirectional reference bridge arm increase sequentially. As the input voltage increases, the unidirectional reference bridge arms are turned off sequentially from low to high reference voltage, achieving smooth and seamless switching of multiple voltage division ratios; voltage division ratio As the bridge arm gradually decreases in closing position, corresponding to the formula above... The coefficient term changes.

[0022] The bidirectional reference bridge arm does not have unidirectional conducting elements. The reference voltage and the sampling node are bidirectionally connected, and the reference voltage participates in the voltage division of the circuit throughout the process to maintain the sampling voltage level reference.

[0023] The voltage divider inflection point, the lowest measurable negative voltage, and the reference voltage of the circuit satisfy the following: Voltage divider inflection point input voltage: in, This indicates the input voltage at the voltage divider inflection point. Indicates the second reference voltage terminal; Minimum measurable negative pressure: in, This indicates the lowest measurable negative pressure.

[0024] The three-arm basic structure achieves two-stage adaptive voltage division switching; based on this, the four-arm structure achieves three-stage adaptive voltage division switching, and the five-arm structure achieves four-stage adaptive voltage division switching, with the voltage division level expanding synchronously with the increase in the number of unidirectional reference arms; in the multi-arm structure, the first... k The input voltage at each voltage divider inflection point satisfies: in, Indicates the first k Input voltage at the voltage divider inflection point k This indicates the number of unidirectional reference arms that have been turned off. Indicates the first k +1 reference voltage.

[0025] The circuit uses all passive components, requiring no operational amplifiers, no external power supply, no power consumption, no circuit noise, and exhibits excellent linearity in the sampling signal; it can operate at any voltage divider level. and All relationships are linear, with only the slope (partial voltage ratio) changing as the bridge arm is turned off, such as... Figure 2 As shown.

[0026] The working principle of the circuit of this invention is as follows: The circuit achieves passive voltage division based on Kirchhoff's current law, requiring no active control devices: (1) When the sampling node voltage ( When the voltage of the unidirectional reference bridge arm is less than the reference voltage of the unidirectional reference bridge arm, the unidirectional conducting element is turned on, the corresponding unidirectional reference bridge arm participates in the parallel voltage division, and the signal level is raised; (2) when the voltage of the sampling node is less than the reference voltage of the unidirectional reference bridge arm, the unidirectional conducting element is turned on, the corresponding unidirectional reference bridge arm participates in the parallel voltage division, and the signal level is raised; When the reference voltage of the unidirectional reference bridge arm is greater than or equal to the reference voltage of the unidirectional reference bridge arm, the unidirectional conduction element is turned off and the corresponding unidirectional reference bridge arm exits the voltage division; (3) the bidirectional reference bridge arm participates in the voltage division throughout the entire process, maintaining the stability of the sampling level; (4) in the high voltage input stage, the bidirectional reference bridge arm participates in the voltage division, resulting in high measurement accuracy; (5) in the low voltage input stage, the unidirectional reference bridge arm participates in the voltage division, raising the signal voltage and slowing down the decrease of the signal voltage, resulting in a wide voltage measurement range.

[0027] Through the above logic, the hardware automatically achieves smooth switching of multiple voltage divider ratios, conditioning the ultra-wide range of positive and negative voltage signals to the safe acquisition range of the ADC.

[0028] In this embodiment, the circuit parameters are: ; , Power supply voltage The ADC voltage range is 0V to 3.3V.

[0029] Working Mode 1: , Unidirectional reference bridge arm conduction, all three bridge arms are voltage divided, adapted to negative to medium voltage signal acquisition, amplification factor 21; Working Mode 2: , Unidirectional reference bridge arm is turned off, only input bridge arm + bidirectional reference bridge arm voltage divider, adapted for high voltage signal acquisition, amplification factor 11; Working Mode 3: , DH Clamped to 3.3V to prevent Overvoltage; Working Mode 4: , DL Clamped to 0V to prevent Negative pressure.

[0030] The bidirectional clamping circuit strictly limits the sampling node voltage between 0V and 3.3V, and can achieve hardware-level protection of the ADC pins regardless of whether the input voltage exceeds the range, ensuring long-term stable operation of the circuit.

[0031] Example 2 In this embodiment, two unidirectional reference arms are added to the basic three-arm bridge structure, with reference voltage... This forms a five-arm or multi-arm structure, such as Figure 3 As shown, a three-stage voltage divider switching is achieved, which further improves the voltage in the middle stage, expands the voltage measurement range, and increases the accuracy of voltage acquisition in the high stage.

[0032] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A wide-range voltage sampling and protection circuit, characterized in that, include: Modular bridge arm circuit, sampling node, and bidirectional clamping protection circuit; The modular bridge arm circuit is based on a three-bridge arm structure, which connects to the sampling node and can be expanded to form a multi-bridge arm structure with four, five, or more bridge arms. The sampling node is connected to the bidirectional clamping protection circuit; The bidirectional clamping protection circuit clamps the sampled voltage within the range of 0V to the supply voltage.

2. The wide-range voltage sampling and protection circuit according to claim 1, characterized in that, The three-arm basic structure includes: an input arm, a unidirectional reference arm, and a bidirectional reference arm; The input bridge arm is connected to the sampling node via the input signal terminal and the first current-limiting resistor, and is used to receive the voltage signal to be collected. The bidirectional reference bridge arm is directly connected to the sampling node via the first reference voltage terminal and the third current-limiting resistor, which is used to realize bidirectional conduction of the level and basic voltage division. The unidirectional reference bridge arm is connected to the sampling node via a second reference voltage terminal, a unidirectional conduction element, and a second current-limiting resistor, in sequence, to realize unidirectional power supply, signal level boosting, anti-backflow control, and automatic switching of voltage divider levels.

3. The wide-range voltage sampling and protection circuit according to claim 1, characterized in that, In the multi-arm structure formed by extending the three-arm basic structure, the newly added arms are all unidirectional reference arms, and each extended unidirectional reference arm is independently equipped with a reference voltage, a unidirectional conduction element and a current limiting resistor.

4. The wide-range voltage sampling and protection circuit according to claim 2, characterized in that, When the circuit is in the fully conducting state of the voltage divider, the input voltage With sampling node voltage The relationship is: in, This represents the first current-limiting resistor. This indicates the third current-limiting resistor. Indicates the first reference voltage terminal. n Indicates the total number of bridge arms. Represented as the first i Reference voltage of the reference bridge arm. Indicates the first i The current-limiting resistor of the bridge arm, Indicates the first i The forward voltage drop of the diode in the unidirectional reference bridge arm.

5. The wide-range voltage sampling and protection circuit according to claim 4, characterized in that, The unidirectional conducting element is a diode, with the anode of the unidirectional conducting element connected to the reference voltage terminal of the corresponding unidirectional reference bridge arm, and the cathode connected to the corresponding current-limiting resistor. The unidirectional reference bridge arm is activated only when the voltage at the sampling node is less than the corresponding reference voltage, and participates in parallel voltage division. When the sampling node voltage is greater than or equal to the corresponding reference voltage, it is turned off, and the unidirectional reference bridge arm exits the voltage divider. At this time, the input voltage... With sampling node voltage The relationship is: 。 6. The wide-range voltage sampling and protection circuit according to claim 1, characterized in that, The bidirectional reference bridge arm does not have unidirectional conducting elements. The reference voltage and the sampling node are bidirectionally connected, and the reference voltage participates in the voltage division of the circuit throughout the process to maintain the sampling voltage level reference.

7. The wide-range voltage sampling and protection circuit according to claim 4, characterized in that, The voltage divider inflection point, the lowest measurable negative voltage, and the reference voltage of the circuit satisfy the following: Voltage divider inflection point input voltage: in, This indicates the input voltage at the voltage divider inflection point. Indicates the second reference voltage terminal; Minimum measurable negative pressure: in, This indicates the lowest measurable negative pressure.

8. The wide-range voltage sampling and protection circuit according to claim 4, characterized in that, The three-bridge arm basic structure realizes two-stage adaptive voltage switching; Based on this, the four-arm structure realizes three-stage adaptive voltage division switching, and the five-arm structure realizes four-stage adaptive voltage division switching. The voltage division level expands synchronously with the increase of the number of unidirectional reference arms. In the multi-arm structure, the first k The input voltage at each voltage divider inflection point satisfies: in, Indicates the first k Input voltage at the voltage divider inflection point k This indicates the number of unidirectional reference arms that have been turned off. Indicates the first k +1 reference voltage.

Images