Current-to-Voltage Converters Information

Last revised: October 25, 2024
Reviewed by: Scott Orlosky, consulting engineer

Current-to-voltage converters are electronic devices that convert current signal inputs to proportional voltage outputs. They include an operational amplifier for simple linear signal processing and a resistor for dissipating current.

The resistance between the operational amplifier’s input and output determines the voltage range for specific current signals. Additional circuitry, such as an instrumentation amplifier, removes small amounts of reverse or dark current. In current-to-voltage converters that handle a range of currents, design considerations account for the DC offset caused by both the input device and the operational amplifier. To remove unwanted signals, current-to-voltage converters often include passive filters that use only capacitors or active filters that use gain and feedback. 

Specifications

Device specifications for current-to-voltage converters include the number of analog channels and the number of differential channels. When single-ended outputs are available, suppliers often specify the maximum number of analog channel outputs as twice the number of differential outputs. Differential channels, which have two inputs, define the voltage as the signal to process between the two inputs.

Other device specifications for current-to-voltage converters include maximum output voltage, accuracy, signal isolation, and multiplexing. Accuracy, which is represented as a percentage of a full measurement range, depends on factors such as signal conditioning linearity, hysteresis, and temperature. Signal isolation can be achieved through optical isolation, magnetic induction, or the use of capacitors. Current-to-voltage converters that include multiplexers can combine several AC or DC inputs serially into one output.

Features

The operational amplifiers that current-to-voltage converters use vary in terms of gain range, programmable gain, and bandwidth. Gain, the factor by which input signals are multiplied, is frequently greater than unity; however, gain can be fractional when a reduction (attenuation) of signal amplitude is desired. Current-to-voltage converters that include operational amplifiers with programmable gain allow users to adjust gain from a local panel or computer interface. Some current-to-voltage converters feature a touch screen. Others provide handheld or programmable devices. Bandwidth, the difference between the high and low limits of the frequency response, is a measurement that is typically defined by a variation from a nominal value by a stated amount such as 3 dB.

Current-to-voltage converters are available in a variety of form factors. Some devices mount on integrated circuits (ICs), standard DIN rails, or printed circuit boards (PCBs) that attach to enclosures or plug into computer backplanes. Others bolt into walls, cabinets, enclosures, or panels. Rack-mounted units fit inside a standard 19 in. telecommunications rack. Modular styles include stackable units that dock in bays, slots, or boxes. Benchtop or freestanding current-to-voltage converters often feature full casings or cabinets and integral interfaces.

Current-to-Voltage Converters FAQs

How do current-to-voltage converters integrate with sensor inputs?

The integration of current-to-voltage converters with sensor inputs is a crucial aspect of engineering applications where sensor signals need to be conditioned and converted for further processing or analysis.

Current-to-voltage converters can interface with a variety of sensor inputs, including accelerometers, thermocouples, thermistors, RTDs (Resistance Temperature Detectors), strain gauges, and more. These sensors often produce current signals that need to be converted into voltage signals for compatibility with other systems.

The primary function of current-to-voltage converters is to scale and convert a current signal input to a desired output voltage range. This conversion is essential for systems that require voltage inputs rather than current inputs.

The input signal to a current-to-voltage converter can have various specifications, such as DC or AC voltage and current, frequency waveforms, or charge from piezoelectric devices. The type of converter selected depends largely on the input signal type and the desired output signal.

These converters are versatile in terms of mounting options and connectivity, allowing them to be integrated into different systems and infrastructures. They can be mounted on DIN rails, PCBs, walls, cabinets, enclosures, panels, rack units, and modular styles that dock in bays or slots.

They can also be connected to host systems using a wide range of interfaces, ensuring compatibility with different systems and communication protocols.

What are the types of sensors that can be used with current-to-voltage converters?

Current-to-voltage converters can interface with a variety of sensor inputs. This allows for wide variation in converting sensor signals into voltage signals for further processing or analysis. Here are some types of sensors that can be used with current-to-voltage converters:

Accelerometers: These sensors measure acceleration forces and are often used in applications such as vibration analysis and motion detection.

Thermocouples: Used for temperature measurement, thermocouples generate a voltage in response to temperature changes, which can be converted into a usable voltage signal.

Thermistors: These temperature-sensitive resistors change resistance with temperature changes and can be used in temperature sensing applications.

RTDs (Resistance Temperature Detectors): RTDs are used for precise temperature measurements and can be integrated with current-to-voltage converters to convert resistance changes into voltage signals.

Strain Gauges: These sensors measure strain on an object and are commonly used in structural engineering and materials testing.

LVDTs (Linear Variable Differential Transformers) and RVDTs (Rotary Variable Differential Transformers): These sensors are used for measuring linear and rotary displacement, respectively.

Specialized Inputs: Other specialized sensor inputs include encoders, counters, tachometers, timers, clocks, relays, and switches, which can also be interfaced with current-to-voltage converters for specific applications.

What are the advantages of using current-to-voltage converters in sensor integration?

The advantages of using current-to-voltage converters in sensor integration are primarily related to their ability to effectively convert and condition sensor signals for further processing or analysis. Here are some key advantages:

Current-to-voltage converters are designed to scale and convert current signal inputs to a desired output voltage range. This conversion is the key to interfacing with systems that require voltage inputs rather than current inputs.

These converters can interface with a wide range of sensor inputs, including accelerometers, thermocouples, thermistors, RTDs, strain gauges, and more. This versatility allows them to be used in diverse applications where different types of sensors are employed.

Current-to-voltage converters offer various physical mounting options, such as DIN rails, printed circuit boards (PCBs), walls, cabinets, enclosures, panels, rack units, and modular styles. This flexibility facilitates their integration into different systems and infrastructures.

They can also be connected to host systems using a wide range of interfaces, ensuring compatibility with different systems and communication protocols.

These converters can handle specialized sensor inputs, such as those from piezoelectric devices, which often require conditioning before they can be used effectively in a system 

These advantages make current-to-voltage converters an essential component in ensuring compatibility and functionality across various engineering systems and applications, particularly when dealing with sensor inputs.

What are the common challenges in integrating current-to-voltage converters with sensors?

Ensuring that the input signal from the sensor is compatible with the current-to-voltage converter is crucial. The input signal could have various specifications, such as DC or AC voltage and current, frequency waveforms, or charge from piezoelectric devices, which may require specific conditioning.

The physical integration of converters with sensors can be challenging due to the variety of mounting options and connectivity interfaces. Converters can be mounted on DIN rails, PCBs, walls, cabinets, and more, and they need to be connected to host systems using interfaces like RS232, RS422, RS485, USB, and others 

Some sensors, such as those using piezoelectric devices, produce specialized inputs that require specific conditioning before conversion. Ensuring that the converter can handle these specialized inputs effectively is a challenge.

Achieving accurate signal conversion from current to voltage is essential for the proper functioning of the system. This requires careful selection and calibration of the converter to match the sensor's output characteristics.

What are the best practices for selecting a current-to-voltage converter for a specific application?

Understand the Input Signal Specifications

Determine the type of input signal you are dealing with, such as DC or AC voltage and current, frequency waveforms, or charge from piezoelectric devices. The converter should be compatible with these specifications to ensure accurate signal conversion.

Compatibility with Sensor Inputs

If the converter will be used with sensors, ensure it can interface with the specific types of sensors involved, such as accelerometers, thermocouples, thermistors, RTDs, strain gauges, etc. This ensures that the sensor signals can be effectively converted into voltage signals for further processing.

Consider Mounting Options

Evaluate the available mounting options for the converter, such as DIN rails, printed circuit boards (PCBs), walls, cabinets, enclosures, panels, rack units, and modular styles. Choose a mounting option that fits well with your existing system infrastructure.

Evaluate Connectivity Interfaces

Check the connectivity options available for the converter, such as RS232, RS422, RS485, USB, IEEE 1394, GPIB, SCSI, TTL, parallel interfaces, Ethernet, modem, or radio or telemetry connections. Ensure that the converter can be easily integrated with your host systems using these interfaces.

Review Performance Specifications

Look into the performance specifications of the converter, including channel specifications, accuracy, resolution, and signal specifications. These factors will influence the converter's ability to meet the demands of your application.

Handling Specialized Inputs

If your application involves specialized inputs, such as those from piezoelectric devices, ensure that the converter can handle these inputs effectively and provide the necessary signal conditioning.

How do current-to-voltage converters differ from other types of signal converters?

Current-to-voltage converters differ from other types of signal converters based on their function and the type of signal conversion they perform. Here are some key differences:

Functionality

Current-to-Voltage Converters: These converters are specifically designed to scale and convert a current signal input into a desired output voltage range. This is essential for interfacing with systems that require voltage inputs rather than current inputs.

Other Signal Converters: Other types of converters perform different functions, such as converting voltage to frequency, frequency to voltage, or handling current loops and charge signals. Each type of converter is tailored to specific signal conversion needs.

Input and Output Specifications

Current-to-Voltage Converters: They handle input signals that are primarily current-based and convert them into voltage signals. The input signal could be DC or AC current, and the output is a voltage signal.

Other Signal Converters: These may handle a variety of input signals, including voltage, frequency, or charge, and convert them into different forms, such as frequency or voltage, depending on the application.

Applications

Current-to-Voltage Converters: Commonly used in applications where sensor signals need to be converted from current to voltage for further processing or analysis. They are often integrated with sensors like accelerometers, thermocouples, and strain gauges.

Other Signal Converters: Used in a wide range of applications, including industrial automation, communication systems, and instrumentation, where different types of signal conversions are required.

Specialized Inputs

Current-to-Voltage Converters: Can handle specialized inputs such as those from piezoelectric devices, which often require conditioning before conversion.

Other Signal Converters: May also handle specialized inputs but are designed for different types of signal conditioning and conversion tasks.

Current-to-Voltage Converters Media Gallery

 

References

GlobalSpec—Signal Conditioners

GlobalSpec—Vibration and Acceleration Signal Conditioners

GlobalSpec—Encoder and Resolver Signal Conditioners

GlobalSpec—Signal Converters

Image credit:

Dataforth Corporation


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