A current-voltage conversion circuit

Abstract

The utility model discloses a current voltage conversion circuit is applied to signal conditioning technical field to solve the problem of low utilization rate of range of current voltage conversion circuit in prior art, specifically includes current acquisition unit for converting the current signal of external current signal output into initial voltage signal, bias voltage unit is used for converting the voltage of external power supply into target bias voltage, and target bias voltage is the minimum voltage value of initial voltage signal, and voltage amplification unit is used for carrying out difference amplification based on initial voltage signal and target bias voltage, and obtains target voltage signal of target range range, and target range range is the full range range of external voltage signal input device. In this way, the dynamic range of signal is effectively translated and amplified as a whole, which makes it match the full range input range of the external voltage signal input device at the back end, thereby fully utilizing the range of the external voltage signal input device, and significantly improving the signal resolution and measurement sensitivity.

Description

Technical Field

[0001] This utility model relates to the field of signal conditioning technology, and in particular to a current-to-voltage conversion circuit. Background Technology

[0002] 4-20mA current signal transmission is a widely used analog signal transmission standard in industrial automation, offering advantages such as strong anti-interference capabilities and long transmission distances. In industrial process control systems, sensors typically convert physical quantities into 4-20mA current signals, which are then transmitted to control equipment via twisted-pair cables. The receiving end needs to use a current-to-voltage conversion circuit to convert the current signal into a voltage signal for sampling and processing by an analog-to-digital converter.

[0003] Currently, current-to-voltage conversion circuits typically use precision resistors as sampling elements to convert 4-20mA current into a 1-5V voltage signal. This design is based on industry standards, with 1V corresponding to 4mA, 5V to 20mA, and a linear variation in between. However, in this conventional design, the converted voltage range is limited to 1-5V, while most ADCs have an input range of 0-5V or even wider. This results in the 0-1V voltage range being completely idle, equivalent to a 20% loss in range utilization, leading to a waste of quantization accuracy. Taking a 12-bit ADC as an example, the theoretical maximum code value is 4095, but due to using only a portion of the input range, the effective code value is reduced to approximately 3276, equivalent to a loss of nearly 1 / 5 of the resolution capability. Existing current-to-voltage conversion circuits suffer from a significant problem of low range utilization, limiting the improvement of overall measurement accuracy. Utility Model Content

[0004] This utility model provides a current-to-voltage conversion circuit to solve the problem of low range utilization in existing current-to-voltage conversion circuits.

[0005] The technical solution provided by this utility model embodiment is as follows: This utility model embodiment provides a current-to-voltage conversion circuit, including: a current acquisition unit, a bias voltage unit, and a voltage amplification unit; The input terminal of the current acquisition unit is connected to an external current signal output device, and the output terminal of the current acquisition unit is connected to the first input terminal of the voltage amplification unit; the input terminal of the bias voltage unit is connected to an external power supply, and the output terminal of the bias voltage unit is connected to the second input terminal of the voltage amplification unit; the output terminal of the voltage amplification unit is connected to an external voltage signal input device. The current acquisition unit is used to convert the current signal output from the external current signal into an initial voltage signal; The bias voltage unit is used to convert the voltage of the external power supply into a target bias voltage; wherein, the target bias voltage is the minimum voltage value of the initial voltage signal; The voltage amplification unit is used to differentially amplify the initial voltage signal and the target bias voltage to obtain the target voltage signal within the target range; wherein, the target range is the full range of the external voltage signal input device.

[0006] Optionally, the voltage amplification unit includes: a first operational amplifier, a first resistor, a second resistor, and a first resistor unit; The non-inverting input of the first operational amplifier is connected to the output of the current acquisition unit via a first resistor, the inverting input of the first operational amplifier is connected to the output of the bias voltage unit via a second resistor, and the output of the first operational amplifier is connected to an external voltage signal input device; the first end of the first resistor unit is connected to the inverting input of the first operational amplifier, and the second end of the first resistor unit is connected to the output of the first operational amplifier.

[0007] Optionally, the bias voltage unit includes: a third resistor, a fourth resistor, and a fifth resistor; The first end of the third resistor is connected to the inverting input of the first operational amplifier, and the second end of the third resistor is connected to ground. The first end of the fourth resistor is connected to the inverting input of the first operational amplifier via the second resistor, and the second end of the fourth resistor is connected to ground. The first end of the fifth resistor is connected to the first end of the fourth resistor, and the second end of the fifth resistor is connected to an external power source.

[0008] Optionally, the bias voltage unit includes: a second operational amplifier, a sixth resistor, a seventh resistor, and an eighth resistor; The first end of the sixth resistor is connected to the external power supply, and the second end of the sixth resistor is connected to ground via the seventh resistor; the non-inverting input of the second operational amplifier is connected to the second end of the sixth resistor via the eighth resistor, the inverting input of the second operational amplifier is connected to the output of the second operational amplifier, and the output of the second operational amplifier is connected to the inverting input of the first operational amplifier via the second resistor.

[0009] Optionally, the current acquisition unit includes: a second resistor unit; The first input terminal of the second resistor unit is connected to an external current signal output device, the second input terminal of the second resistor unit is connected to ground, the first output terminal of the second resistor unit is connected to the non-inverting input terminal of the first operational amplifier via the first resistor, and the second output terminal of the second resistor unit is connected to ground.

[0010] Optionally, the current acquisition unit may also include: a third operational amplifier, a ninth resistor, a tenth resistor, an eleventh resistor, and a twelfth resistor; The non-inverting input of the third operational amplifier is connected to the first output of the second resistor unit via the ninth resistor, the inverting input of the third operational amplifier is connected to the second output of the second resistor unit via the tenth resistor, and the output of the third operational amplifier is connected to the non-inverting input of the first operational amplifier via the first resistor. The first terminal of the eleventh resistor is connected to the non-inverting input terminal of the third operational amplifier, and the second terminal of the eleventh resistor is connected to ground. The first end of the twelfth resistor is connected to the inverting input of the third operational amplifier, and the second end of the twelfth resistor is connected to the output of the third operational amplifier.

[0011] Optionally, the current-to-voltage conversion circuit may also include a filter unit; The filtering unit is located at the output of the voltage amplification unit and connected to an external voltage signal input device. The filtering unit is used to filter out noise in the target voltage signal.

[0012] Optionally, the filter unit includes: a thirteenth resistor and a first capacitor; The thirteenth resistor is connected in series between the output of the voltage amplifier unit and the external voltage signal input device; The first terminal of the first capacitor is connected between the thirteenth resistor and the external voltage signal input device, and the second terminal of the first capacitor is connected to ground.

[0013] Optionally, the current-to-voltage conversion circuit may also include: an overcurrent protection unit; The overcurrent protection unit is connected in series between the input terminal of the current acquisition unit and the external current signal output device; The overcurrent protection unit is used to disconnect the connection between the input terminal of the current acquisition unit and the external current signal output device when the current value corresponding to the current signal output by the external current signal exceeds the preset safe current threshold.

[0014] Optionally, the overcurrent protection unit includes: a fuse or circuit breaker; A fuse or circuit breaker is connected in series between the input terminal of the current acquisition unit and the external current signal output device. The beneficial effects of this embodiment are as follows: In this embodiment of the invention, the current-to-voltage conversion circuit converts the external current signal output into an initial voltage signal and generates a target bias voltage corresponding to the minimum voltage value of the initial voltage signal. Through differential amplification, a target voltage signal matching the full range of the external voltage signal input device is obtained. This design effectively shifts and amplifies the overall dynamic range of the signal, matching it to the full input range of the connected external voltage signal input device. This fully utilizes the range of the external voltage signal input device, significantly improving signal resolution and measurement sensitivity. Furthermore, since the target voltage signal output by the voltage amplification unit can match the full range of the external voltage signal input device, the circuit's adaptability and applicability are enhanced.

[0015] Other features and advantages of this invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of this invention, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the first circuit structure of the current-voltage conversion circuit in this embodiment of the present invention; Figure 2 This is a schematic diagram of a second circuit structure for the current-to-voltage conversion circuit in an embodiment of this utility model; Figure 3 This is a schematic diagram of the third circuit structure of the current-to-voltage conversion circuit in this embodiment of the present invention; Figure 4 This is a schematic diagram of the fourth circuit structure of the current-to-voltage conversion circuit in this embodiment of the present invention; Figure 5 This is a schematic diagram of the fifth circuit structure of the current-voltage conversion circuit in this embodiment of the present invention; Figure 6 This is a schematic diagram of the sixth circuit structure of the current-voltage conversion circuit in this embodiment of the present invention; Figure 7 This is a schematic diagram of the seventh circuit structure of the current-voltage conversion circuit in this embodiment of the present invention; Figure 8 This is a schematic diagram of the eighth circuit structure of the current-voltage conversion circuit in this utility model embodiment; Figure 9This is a schematic diagram of the ninth circuit structure of the current-voltage conversion circuit in this embodiment of the present invention.

[0017] Icons: 100 - Current-to-voltage conversion circuit; 110 - Current acquisition unit; 111 - Second resistor unit; 120 - Bias voltage unit; 130 - Voltage amplification unit; 131 - First resistor unit; 140 - Filtering unit; 150 - Overcurrent protection unit; A1 - First operational amplifier; R1 - First resistor; R2 - Second resistor; R3 - Third resistor; R4 - Fourth resistor; R5 - Fifth resistor; A2 - Second operational amplifier; R6 - Sixth resistor; R7 - Seventh resistor; R8 - Eighth resistor; A3 - Third operational amplifier; R9 - Ninth resistor; R10 - Tenth resistor; R11 - Eleventh resistor; R12 - Twelfth resistor; R13 - Thirteenth resistor; C1 - First capacitor. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] This utility model embodiment provides a current-to-voltage conversion circuit, see reference. Figure 1 As shown, the current-to-voltage conversion circuit 100 includes at least: a current acquisition unit 110, a bias voltage unit 120, and a voltage amplification unit 130. The input terminal of the current acquisition unit 110 is connected to an external current signal output device, and the output terminal of the current acquisition unit 110 is connected to the first input terminal of the voltage amplification unit 130; the input terminal of the bias voltage unit 120 is connected to an external power supply, and the output terminal of the bias voltage unit 120 is connected to the second input terminal of the voltage amplification unit 130; the output terminal of the voltage amplification unit 130 is connected to an external voltage signal input device. The current acquisition unit 110 is used to convert the current signal output from the external current signal into an initial voltage signal; The bias voltage unit 120 is used to convert the voltage of the external power supply into a target bias voltage; wherein, the target bias voltage is the minimum voltage value of the initial voltage signal; The voltage amplification unit 130 is used to perform differential amplification based on the initial voltage signal and the target bias voltage to obtain the target voltage signal within the target range; wherein, the target range is the full range of the external voltage signal input device.

[0020] exist Figure 1In the current-to-voltage conversion circuit 100 shown, the input terminal of the current acquisition unit 110 is connected to an external current signal output device to receive a current signal. This external current signal output device can be a sensor, transmitter, or similar device, and the current signal is an industry-standard 4-20mA signal. The current acquisition unit 110 linearly converts this changing current signal into an initial voltage signal. The input terminal of the bias voltage unit 120 is connected to an external power supply, which can be a +5V or +15V power supply. The bias voltage unit 120 is used to generate a stable and accurate target bias voltage. The target bias voltage value is specifically set to be equal to or very close to the minimum voltage value of the aforementioned initial voltage signal. When the input current is 4mA, the minimum initial voltage signal output by the current acquisition unit 110 is 1V. At this time, the bias voltage unit 120 is designed to output a 1V target bias voltage. This 1V target bias voltage will serve as a reference for subsequent differential amplification, i.e., providing a reference offset. The first input terminal of the voltage amplification unit 130 receives the initial voltage signal from the current acquisition unit 110, and the second input terminal receives the target bias voltage from the bias voltage unit 120. The output terminal of the voltage amplification unit 130 is connected to an external voltage signal input device, such as the ADC pin of a microcontroller (MCU). The voltage amplification unit 130 differentially amplifies the two input voltage signals, that is, it calculates the difference between the initial voltage signal and the target bias voltage, and amplifies this difference to obtain the target voltage signal within the target range. The target range is the full range of the external voltage signal input device, i.e., the input voltage range of the external voltage signal input device. Since the target bias voltage is set to the minimum value of the initial voltage signal, this is equivalent to subtracting the bias from the initial voltage signal. Thus, when the input current is 4mA, the initial voltage is 1V, the target bias voltage is also 1V, the difference between the two is 0V, and the circuit ultimately outputs 0V. When the input current is 20mA, the initial voltage is 5V, and the difference between this and the target bias voltage of 1V is 4V. This expands the voltage range of 0-4V to the full range of 0-5V of the external voltage signal input device, thereby making full use of the range of the external voltage signal input device and improving the resolution.

[0021] In this way, the current-to-voltage conversion circuit can convert the external current signal output into an initial voltage signal and generate a target bias voltage corresponding to the minimum voltage value of the initial voltage signal. Through differential amplification, a target voltage signal matching the full range of the external voltage signal input device is obtained. This design effectively shifts and amplifies the overall dynamic range of the signal, matching it to the full input range of the connected external voltage signal input device. This fully utilizes the range of the external voltage signal input device, significantly improving signal resolution and measurement sensitivity. Furthermore, since the target voltage signal output by the voltage amplification unit can match the full range of the external voltage signal input device, the circuit's adaptability and applicability are enhanced.

[0022] In one possible implementation, see [reference] Figure 2 As shown, the voltage amplification unit 130 includes: a first operational amplifier A1, a first resistor R1, a second resistor R2, and a first resistor unit 131; The non-inverting input of the first operational amplifier A1 is connected to the output of the current acquisition unit 110 via the first resistor R1, the inverting input of the first operational amplifier A1 is connected to the output of the bias voltage unit 120 via the second resistor R2, and the output of the first operational amplifier A1 is connected to an external voltage signal input device; the first end of the first resistor unit 131 is connected to the inverting input of the first operational amplifier A1, and the second end of the first resistor unit 131 is connected to the output of the first operational amplifier A1.

[0023] exist Figure 2 In the current-to-voltage conversion circuit 100 shown, the voltage amplification unit 130 can be constructed from a standard differential amplifier circuit. This circuit consists of a first operational amplifier A1, a first resistor R1, a second resistor R2, and a first resistor unit 131 serving as a feedback resistor. The first resistor unit 131 includes at least one resistor, and the number and value of the resistors in the first resistor unit 131 are determined according to the amplification factor. When the first resistor unit 131 includes multiple resistors, the multiple resistors are connected in series. The non-inverting input terminal of the first operational amplifier A1 is connected to the output terminal of the current acquisition unit 110 through the first resistor R1 to receive the initial voltage signal. The inverting input terminal of the first operational amplifier A1 is connected to the output terminal of the bias voltage unit 120 through the second resistor R2 to receive the target bias voltage. The first resistor unit 131 is connected between the inverting input terminal and the output terminal of the first operational amplifier A1, forming negative feedback. The amplification factor of this differential amplifier circuit is determined by the ratio of the resistance value of the first resistor unit 131 to the resistance value of the second resistor R2, as well as the matching degree of other related resistors. It can be flexibly configured according to actual needs to achieve signal offset and amplification functions, and linearly map the voltage range to the full range of the external voltage signal input device.

[0024] In one possible implementation, see [reference] Figure 3 As shown, the bias voltage unit 120 includes: a third resistor R3, a fourth resistor R4, and a fifth resistor R5; The first end of the third resistor R3 is connected to the inverting input of the first operational amplifier A1, and the second end of the third resistor R3 is connected to ground. The first end of the fourth resistor R4 is connected to the inverting input of the first operational amplifier A1 via the second resistor R2, and the second end of the fourth resistor R4 is connected to ground. The first end of the fifth resistor R5 is connected to the first end of the fourth resistor R4, and the second end of the fifth resistor R5 is connected to an external power supply.

[0025] exist Figure 3 In the current-to-voltage conversion circuit 100 shown, the third resistor R3, the fourth resistor R4, and the fifth resistor R5 form a resistor voltage divider structure. Utilizing the principle of resistor voltage division, the desired target bias voltage can be obtained at a specific node by appropriately setting the resistor values.

[0026] In one possible implementation, see [reference] Figure 4 As shown, the bias voltage unit 120 includes: a second operational amplifier A2, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8; The first end of the sixth resistor R6 is connected to the external power supply, and the second end of the sixth resistor R6 is connected to ground via the seventh resistor R7; the non-inverting input of the second operational amplifier A2 is connected to the second end of the sixth resistor R6 via the eighth resistor R8, the inverting input of the second operational amplifier A2 is connected to the output of the second operational amplifier A2, and the output of the second operational amplifier A2 is connected to the inverting input of the first operational amplifier A1 via the second resistor R2.

[0027] exist Figure 4 In the current-to-voltage conversion circuit 100 shown, the sixth resistor R6 and the seventh resistor R7 first divide the voltage of the external power supply to obtain a preliminary reference voltage. This reference voltage is sent to the non-inverting input of the second operational amplifier A2 through the eighth resistor R8. The inverting input of the second operational amplifier A2 is directly connected to its output, forming a voltage follower. The voltage follower formed by the operational amplifier has high input impedance and extremely low output impedance, which can provide a very stable and powerful target bias voltage for the subsequent voltage amplification unit 130. It will not fluctuate due to the load effect of the subsequent circuit, thus significantly improving the accuracy and anti-interference capability of the entire conversion circuit.

[0028] In one possible implementation, see [reference] Figure 5 As shown, the current acquisition unit 110 includes: a second resistor unit 111; The first input terminal of the second resistor unit 111 is connected to an external current signal output device, the second input terminal of the second resistor unit 111 is connected to ground, the first output terminal of the second resistor unit 111 is connected to the non-inverting input terminal of the first operational amplifier A1 via the first resistor R1, and the second output terminal of the second resistor unit 111 is connected to ground.

[0029] exist Figure 5 In the current-to-voltage conversion circuit 100 shown, the second resistor unit 111 linearly converts the current signal into an initial voltage signal, realizing basic current-to-voltage conversion. The current acquisition unit 110 can be composed of a single second resistor unit 111, which includes at least one precision sampling resistor. The number and resistance value of the sampling resistors are determined according to the current signal conversion requirements and the magnitude of the initial voltage signal. When the second resistor unit 111 includes multiple sampling resistors, these resistors are connected in series.

[0030] In specific implementation, the second resistor unit 111 consists of resistors with resistances of 150Ω and 100Ω connected in series, and the first resistor unit 131 consists of resistors with resistances of 15kΩ and 2kΩ connected in series; the first resistor R1 has a resistance of 10kΩ; the second resistor R2 has a resistance of 200kΩ; the third resistor R3 has a resistance of 100kΩ; the fourth resistor R4 has a resistance of 100kΩ; and the fifth resistor R5 has a resistance of 2kΩ. The output voltage of the external power supply is 15V. +Vcc is +15V, and -Vcc is -15V. The voltage V at the non-inverting input terminal of the first operational amplifier A1 is... + for: V + =(0.150+0.100)*Iin=0.25 Iin Where Iin is the input current of the current-to-voltage conversion circuit.

[0031] The voltage Vx at node X between the fifth resistor R5 and the fourth resistor R4 is: =14.5631+0.0097

[0032] Where V- is the voltage at the inverting input terminal of the first operational amplifier A1.

[0033] The voltage V- at the inverting input of the first operational amplifier A1 is:

[0034] in, This is the voltage output of the first operational amplifier A1.

[0035] Due to V + =V -Combining the above formulas, we can obtain:

[0036] When Iin = 4mA =0.0161V; at Iin=10mA, =1.897V; at Iin=20mA, =5.032V.

[0037] In one possible implementation, see [reference] Figure 6 As shown, the current acquisition unit 110 also includes: a third operational amplifier A3, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, and a twelfth resistor R12; The non-inverting input terminal of the third operational amplifier A3 is connected to the first output terminal of the second resistor unit 111 via the ninth resistor R9, the inverting input terminal of the third operational amplifier A3 is connected to the second output terminal of the second resistor unit 111 via the tenth resistor R10, and the output terminal of the third operational amplifier A3 is connected to the non-inverting input terminal of the first operational amplifier A1 via the first resistor R1. The first terminal of the eleventh resistor R11 is connected to the non-inverting input terminal of the third operational amplifier A3, and the second terminal of the eleventh resistor R11 is connected to ground. The first end of the twelfth resistor R12 is connected to the inverting input of the third operational amplifier A3, and the second end of the twelfth resistor R12 is connected to the output of the third operational amplifier A3.

[0038] exist Figure 6 In the current-to-voltage conversion circuit 100 shown, a buffer amplification stage is added to the original second resistor unit 111, consisting of a third operational amplifier A3, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, and a twelfth resistor R12. This buffer amplification stage buffers the voltage across the second resistor unit 111, significantly improving the input impedance and suppressing common-mode noise. This minimizes the impact on the external current output device when the circuit is connected to the measurement loop. In the case where the current acquisition unit 110 also includes the third operational amplifier A3, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, and the twelfth resistor R12, the voltage amplification unit 130 also includes an adjustment resistor R0. The first end of the adjustment resistor R0 is connected to the non-inverting input of the first operational amplifier A1, and the second end of the adjustment resistor R0 is connected to ground.

[0039] In one possible implementation, see [reference] Figure 7 As shown, the current-to-voltage conversion circuit 100 also includes a filter unit 140; The filter unit 140 is located at the output terminal of the voltage amplifier unit 130 and is connected to an external voltage signal input device. The filter unit 140 is used to filter out noise in the target voltage signal.

[0040] exist Figure 7 In the current-to-voltage conversion circuit 100 shown, the filter unit 140 can effectively filter out high-frequency noise and interference signals carried in the target voltage signal, improve signal quality, and make the voltage signal output to the external voltage signal input device smoother and more stable, thereby improving the accuracy of the measurement results.

[0041] In one possible implementation, see [reference] Figure 8 As shown, the filter unit 140 includes: a thirteenth resistor R13 and a first capacitor C1; The thirteenth resistor R13 is connected in series between the output terminal of the voltage amplifier unit 130 and the external voltage signal input device; The first terminal of the first capacitor C1 is connected between the thirteenth resistor R13 and the external voltage signal input device, and the second terminal of the first capacitor C1 is connected to ground.

[0042] exist Figure 8 In the current-to-voltage conversion circuit 100 shown, the thirteenth resistor R13 and the first capacitor C1 constitute an RC low-pass filter. The thirteenth resistor R13 is connected in series in the signal output path, used for current limiting and, together with the first capacitor C1, forming a filtering time constant. One end of the first capacitor C1 is connected between the thirteenth resistor R13 and the external voltage signal input device, and the other end is grounded, used to shunt high-frequency noise signals to ground. The RC filter can effectively filter out high-frequency noise or glitches that may exist in the target voltage signal, ensuring that the target voltage signal received from the external voltage signal input is smooth and stable.

[0043] In specific implementation, the second resistor unit 111 consists of two resistors connected in series, one with a resistance of 150Ω and the other with a resistance of 100Ω. The first resistor unit 131 consists of a resistor with a resistance of 15kΩ. The resistance of resistor R0 is 15 kΩ; the resistance of the first resistor R1 is 12kΩ; the resistance of the second resistor R2 is 12kΩ; the resistance of the sixth resistor R6 is 12kΩ; the resistance of the seventh resistor R7 is 3kΩ; the resistance of the eighth resistor R8 is 10kΩ; the resistance of the ninth resistor R9 is 10kΩ; the resistance of the tenth resistor R10 is 10kΩ; the resistance of the eleventh resistor R11 is 10kΩ; the resistance of the twelfth resistor R12 is 10kΩ; the resistance of the thirteenth resistor R13 is 330Ω; and the capacitance of the first capacitor C1 is 10nF. The output voltage of the external power supply is 5V. +Vcc is +5V, and -Vcc is -5V.

[0044] In one possible implementation, see [reference] Figure 9 As shown, the current-to-voltage conversion circuit 100 also includes an overcurrent protection unit 150; The overcurrent protection unit 150 is connected in series between the input terminal of the current acquisition unit 110 and the external current signal output device. The overcurrent protection unit 150 is used to disconnect the connection between the input terminal of the current acquisition unit 110 and the external current signal output device when the current value corresponding to the current signal output by the external current signal exceeds the preset safe current threshold.

[0045] exist Figure 9 In the current-to-voltage conversion circuit 100 shown, considering the possibility of malfunction in the external current output device leading to excessive current in the input current-to-voltage conversion circuit 100, an overcurrent protection unit 150 is installed between the input terminal of the current acquisition unit 110 and the external current signal output device to protect the internal components from burnout. The overcurrent protection unit 150 monitors the current value corresponding to the current signal output from the external current signal in real time. When the current value exceeds a preset safe current threshold, it automatically disconnects the connection between the input terminal of the current acquisition unit 110 and the external current signal output device to protect the subsequent circuits.

[0046] Specifically, the overcurrent protection unit includes: a fuse or circuit breaker; A fuse or circuit breaker is connected in series between the input terminal of the current acquisition unit and the external current signal output device.

[0047] In practical applications, when an external current signal output device malfunctions, causing the current value corresponding to the current signal to exceed a preset safe current threshold, the fuse or circuit breaker will irreversibly melt based on the principle of current thermal effect, thereby completely severing the electrical connection between the preceding external current signal and the subsequent current-to-voltage conversion circuit. This hardware protection mechanism provides intrinsically safe overcurrent protection for the current-to-voltage conversion circuit, effectively preventing component damage caused by abnormally large currents, and significantly improving the reliability and safety of the circuit in industrial application environments.

[0048] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0049] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this utility model without departing from the spirit and scope of the embodiments of this utility model. Therefore, if these modifications and variations to the embodiments of this utility model fall within the scope of the claims of this utility model and their equivalents, then this utility model also intends to include these modifications and variations.

Claims

1. A current-to-voltage conversion circuit, characterized in that, include: Current acquisition unit, bias voltage unit, and voltage amplification unit; The input terminal of the current acquisition unit is connected to an external current signal output device, and the output terminal of the current acquisition unit is connected to the first input terminal of the voltage amplification unit. The input terminal of the bias voltage unit is connected to an external power supply, and the output terminal of the bias voltage unit is connected to the second input terminal of the voltage amplification unit; the output terminal of the voltage amplification unit is connected to an external voltage signal input device. The current acquisition unit is used to convert the current signal output from the external current signal into an initial voltage signal; The bias voltage unit is used to convert the voltage of the external power supply into a target bias voltage; wherein, the target bias voltage is the minimum voltage value of the initial voltage signal; The voltage amplification unit is used to differentially amplify the initial voltage signal and the target bias voltage to obtain a target voltage signal within the target range; wherein, the target range is the full range of the external voltage signal input device.

2. The current-to-voltage conversion circuit as described in claim 1, characterized in that, The voltage amplification unit includes: a first operational amplifier, a first resistor, a second resistor, and a first resistor unit; The non-inverting input of the first operational amplifier is connected to the output of the current acquisition unit via a first resistor, the inverting input of the first operational amplifier is connected to the output of the bias voltage unit via a second resistor, and the output of the first operational amplifier is connected to an external voltage signal input device; the first end of the first resistor unit is connected to the inverting input of the first operational amplifier, and the second end of the first resistor unit is connected to the output of the first operational amplifier.

3. The current-to-voltage conversion circuit as described in claim 2, characterized in that, The bias voltage unit includes: a third resistor, a fourth resistor, and a fifth resistor; The first end of the third resistor is connected to the inverting input of the first operational amplifier, and the second end of the third resistor is connected to ground. The first end of the fourth resistor is connected to the inverting input of the first operational amplifier via the second resistor, and the second end of the fourth resistor is connected to ground. The first end of the fifth resistor is connected to the first end of the fourth resistor, and the second end of the fifth resistor is connected to an external power source.

4. The current-to-voltage conversion circuit as described in claim 2, characterized in that, The bias voltage unit includes: a second operational amplifier, a sixth resistor, a seventh resistor, and an eighth resistor; The first end of the sixth resistor is connected to an external power supply, and the second end of the sixth resistor is connected to ground via the seventh resistor; the non-inverting input of the second operational amplifier is connected to the second end of the sixth resistor via the eighth resistor, the inverting input of the second operational amplifier is connected to the output of the second operational amplifier, and the output of the second operational amplifier is connected to the inverting input of the first operational amplifier via the second resistor.

5. The current-to-voltage conversion circuit as described in claim 3 or 4, characterized in that, The current acquisition unit includes: a second resistor unit; The first input terminal of the second resistor unit is connected to an external current signal output device, the second input terminal of the second resistor unit is connected to ground, the first output terminal of the second resistor unit is connected to the non-inverting input terminal of the first operational amplifier via the first resistor, and the second output terminal of the second resistor unit is connected to ground.

6. The current-to-voltage conversion circuit as described in claim 5, characterized in that, The current acquisition unit also includes: a third operational amplifier, a ninth resistor, a tenth resistor, an eleventh resistor, and a twelfth resistor; The non-inverting input terminal of the third operational amplifier is connected to the first output terminal of the second resistor unit via the ninth resistor, the inverting input terminal of the third operational amplifier is connected to the second output terminal of the second resistor unit via the tenth resistor, and the output terminal of the third operational amplifier is connected to the non-inverting input terminal of the first operational amplifier via the first resistor. The first end of the eleventh resistor is connected to the non-inverting input of the third operational amplifier, and the second end of the eleventh resistor is connected to ground. The first end of the twelfth resistor is connected to the inverting input of the third operational amplifier, and the second end of the twelfth resistor is connected to the output of the third operational amplifier.

7. The current-to-voltage conversion circuit as described in claim 6, characterized in that, Also includes: Filtering unit; The filtering unit is located at the output terminal of the voltage amplification unit and connected to an external voltage signal input device. The filtering unit is used to filter out noise in the target voltage signal.

8. The current-to-voltage conversion circuit as described in claim 7, characterized in that, The filtering unit includes: a thirteenth resistor and a first capacitor; The thirteenth resistor is connected in series between the output terminal of the voltage amplification unit and the external voltage signal input device; The first terminal of the first capacitor is connected between the thirteenth resistor and the external voltage signal input device, and the second terminal of the first capacitor is connected to ground.

9. The current-to-voltage conversion circuit as described in claim 7, characterized in that, Also includes: Overcurrent protection unit; The overcurrent protection unit is connected in series between the input terminal of the current acquisition unit and the external current signal output device. The overcurrent protection unit is used to disconnect the connection between the input terminal of the current acquisition unit and the external current signal output device when the current value corresponding to the current signal output by the external current signal exceeds a preset safe current threshold.

10. The current-to-voltage conversion circuit as described in claim 9, characterized in that, The overcurrent protection unit includes: a fuse or circuit breaker; The fuse or circuit breaker is connected in series between the input terminal of the current acquisition unit and the external current signal output device.

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