SY 4-20mA-O Two-Wire Passive Current to Voltage Converter

Sunyuan SY 4-20mA-O is a kind of low cost small size 2-wire passive 4-20mA to voltageconversionIC,itcan convert active 4-20mA signal input into voltage signal output. In designing the converter, 2-wireinputlooppowered technique is adopted, and the external power supply is not required which simplifies customers’ designplan and reduce customers’ cost. Inside the conversion IC, current signal conversion circuit, power invertingcircuit, subtraction circuit and buffered output circuit are integrated. Very low input equivalent impedanceenablesthe IC to collect current signals from sensor signal output loop circuit and when the input is 30mAsignalthevoltage drop is ≤6V. That 2-wire passive 4-20ma to voltage conversion IC achieves long-distancenon-distortedtransmission without external power supply.

SY 4-20mA-O Series are mainly applied in low cost 4-20mA current to voltage signal design, noexternalpower supply which makes it easy in wire connection, and achieves low power consumption, lowheat andhighperformance. The main features of that conversion IC are: 2-wire loop powered without external powersupply,subtraction circuit and amplification buffered output circuit are integrated into the IC, high reliabilityandeasytouse. The converter convert 4-20mA output signal from sensor, PLC, it means that the transmissionof electricpower, so there is power consumption internally. In that conditions, it requires that 4-20mAsourcesignal shouldbe able to drive 300Ω load, thus the converter IC can operate normally. In industrial site applications, mostofmeters and instruments, sensors, PLC, DCS, etc have the capacity to drive 300Ω load. In industrial site, in some conditions only one piece of IV conversion sampling resistanceisenoughtoconvert current signal into voltage signal. That kind of circuit is easy but not much reliable. First, whenthesignalis in zero point, there is zero current in sampling resistance, for example, convert 4-0mA into max. 5VDC,inthezero point, it is 1V after conversion, that 1V voltage can be processed by microprocessor softwareif available.Inthat case, the available voltage left 5-1=4VDC, it is not 5VDC. The max. input voltage of microprocessor(A/D)isit’s power supply, usually 5VDC, so it is much more complicated in deal with such simple input conversioncircuits,in order to get the A/D conversion bits, it will increase the IC costs accordingly. The simplest methodindealingwith the problems above is that adding a subtraction and buffered processing circuit madebyoperationalamplifier in the input terminal of microprocessor, that circuit is convenient to process zero signal andsavethemicroprocessor resource to ensure that all the resource is used in signal conversion especially inA-Dconversion applications.

Sunyuan low cost small size I/V converter SY 4-20MA-O is designed to solved the problemsaboveinindustrial site. That 4-20mA to voltage conversion IC not only realize the conversion between current andvoltagesignal, it also operates in low heat and passive mode to meet the application requirements in A/Dinterfacedataacquisition and signal conversion.

It greatly reduce user’s cost and the internal resource consumption in choosing microprocessor andprovidesimplest solutions to the developers.