2-wire Passive 4-20mA to Voltage Signal Isolation Converter
ISO 4-20MA-O Series
2-wire 4-20mA to Voltage Transmitter Features:
>> High efficient signal loop stealing technology, external power supply is not required.
>> 2-wire 4-20mA standard analog signal input,
0-2.5V/0-3.3V/0-5V/1-5V, etc standard voltage signal output.
>> Extra low input impedance, meet the requirements that when input is 20mA the voltage drop ≤9V.
>> Accuracy grade: 0.1, 0.2, 0.5
>> High linearity in full measuring range, non-linearity error grade <0.2%
>> 3000VDC isolation between input and output.
>> Industrial grade temperature range: -25 ~ +70 ºC
>>Small size standard SIP 7Pin, UL94V-0 flame-retardant package.
2-wire 4-20mA to Voltage Transmitter Applications:
>>Sensor 4-20mA signal acquisition and conversion.
>>Industrial site signal acquisition and long-distance transmission.
>> Analog signal conversion and data acquisition.
>>Sensors' or meters' Signal receiving and transmission.
>>PLC, DCS analog signal acquisition and conversion.
>>Power control, medical equipment monitoring.
>> 4-20mA current signal to voltage signal conversion: 1-IN1-OUT, 2-IN 2-OUT, 3-IN 3-OUT.
| Input |
Output (loop powered) |
| 4-20mA |
0-2.5V |
| 0-5V |
| 0-10V |
| 0-3.3V |
2-wire Passive 4-20mA to Voltage Signal Isolation Converter Introduction:
Sunyuan ISO 4-20mA-O is a kind of low cost small size 2-wire passive 4-20mA to voltage conversion IC, it can convert active 4-20mA signal input into voltage signal output. In designing the converter, 2-wire input loop powered technique is adopted, and the external power supply is not required which simplifies customers' design plan and reduce customers' cost. Inside the conversion IC, current signal conversion circuit, power inverting circuit, subtraction circuit and buffered output circuit are integrated. Very low input equivalent impedance enables the IC to collect current signals from sensor signal output loop circuit and when the input is 30mA signal the voltage drop is ≤9V. That 2-wire passive 4-20ma to voltage conversion IC achieves long-distance non-distorted transmission without external power supply.
ISO 4-20mA-O Series are mainly applied in low cost 4-20mA current to voltage signal design, no external power supply which makes it easy in wire connection, and achieves low power consumption, low heat and high performance. The main features of that conversion IC are: 2-wire loop powered without external power supply, subtraction circuit and amplification buffered output circuit are integrated into the IC, high reliability and easy to use. The converter convert 4-20mA output signal from sensor, PLC, it means that the transmission of electric power, so there is power consumption internally. In that conditions, it requires that 4-20mA source signal should be able to drive 450Ω load, thus the converter IC can operate normally. In industrial site applications, most of meters and instruments, sensors, PLC, DCS, etc have the capacity to drive 450Ω load.
In industrial site, in some conditions only one piece of IV conversion sampling resistance is enough to convert current signal into voltage signal. That kind of circuit is easy but not much reliable. First, when the signal is in zero point, there is zero current in sampling resistance, for example, convert 4-0mA into max. 5VDC, in the zero point, it is 1V after conversion, that 1V voltage can be processed by microprocessor software if available. In that case, the available voltage left 5-1=4VDC, it is not 5VDC. The max. input voltage of microprocessor (A/D) is it's power supply, usually 5VDC, so it is much more complicated in deal with such simple input conversion circuits, in order to get the A/D conversion bits, it will increase the IC costs accordingly. The simplest method in dealing with the problems above is that adding a subtraction and buffered processing circuit made by operational amplifier in the input terminal of microprocessor, that circuit is convenient to process zero signal and save the microprocessor resource to ensure that all the resource is used in signal conversion especially in A-D conversion applications.
Sunyuan low cost small size I/V converter ISO 4-20MA-O is designed to solved the problems above in industrial site. That 4-20mA to voltage conversion IC not only realize the conversion between current and voltage signal, it also operates in low heat and passive mode to meet the application requirements in A/D interface data acquisition and signal conversion.It greatly reduce user's cost and the internal resource consumption in choosing microprocessor and provide simplest solutions to the developers.
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