10KVAC High Isolation Two Wire Loop Powered 4-20mA to Voltage Signal Converters
SunYuan ISOH 4-20mA-O is the highest isolation voltage 10KVAC in the industry fied, small size (16pin single-line SIP16 Pin) low cost, two-wire passive 4-20mA to voltage signal isolation converter module. The voltage signal value can be converted by sampling acquisition isolation in a two-wire passive 4-20mA current loop without a separate power supply. The IC adopts two-wire input loop power supply mode, unique high-efficiency signal loop power-taking technology and no external working power supply, which can greatly simplify the user's system design and reduce the user wiring cost. The internet of IC including a current signal modulation and demodulation circuit, a signal coupling isolation conversion circuit, a power supply inverter circuit, a subtraction circuit, a buffer processing output circuit, etc., and a small input equivalent resistance enables the IC to be used from instruments, PLCs, and sensors. The current signal is collected in the signal loop (the voltage drop when the input 20mA signal is reached), and the collected current signal is isolated and converted into a voltage signal. It is convenient to realize the AD acquisition and conversion of the industrial field MCU microcontroller, DCS, FCS and other control systems. It meets the needs of the user's site without the need for an external auxiliary power supply or IV conversion transmitter to achieve long-distance, distortion-free transmission of signals.
ISOH 4-20mA-O is often used for the isolation conversion of two-wire passive 4-20mA current to voltage signals. It has low power consumption and low heat generation (basically no temperature rise)high reliability. The internet mainly including the subtraction circuit and the amplifier buffer output circuit. These circuits bring the advantages of simplicity and reliability and also bring the limitations of use. Both the product and the 4-20 mA signal output from the sensor are isolated and transmitted from the other. From another definition it is the transmission of electric power, so there must be power loss inside. This loss is expressed in the product of the input current value and its own input voltage drop. In this case, the 4-20 mA source must have the ability to drive a 500 load for the product to function properly. At present, from the practical application experience of industrial sites, most of the field instruments and sensors, PLC / DCS, etc. can meet the ability of 4-20mA signal output to drive 500 load.
In industrial field applications, some circuits can convert the input current signal into a voltage signal using only one I/V conversion sampling resistor. This circuit is simple but not practical. First of all, when the actual meaning is zero signal, there will be a zero current flowing through the sampling resistor. If the input current is converted to the maximum 5V voltage according to the 4~20mA input current, the zero point happens to be 1V. This 1V is sufficient in the MCU resources. At that time, it can be subtracted by the microcontroller software, but the useful voltage will leave 5-1=4VDC instead of 5VDC. Since the maximum input voltage of the A/D of the MCU is the supply voltage of the MCU, this voltage is usually 5 VDC, so it is very trouble to deal with this simple input conversion circuit. In order to achieve the number of A/D conversions, the cost of the chip will increase. . A simple way to solve the above problem is to configure a subtraction and buffer processing circuit composed of an operational amplifier before the input of the single-chip microcomputer. Increasing this level of circuit can make the processing of the zero point more convenient, without consuming the internal resources of the single-chip microcomputer, especially the single-chip microcomputer. When the A/D interface is used to accept such a zero signal and the input is not zero voltage value, the resources of the A/D conversion bit number can be fully applied to the useful signal.
ISOH 4-20mA-O series enables high-precision, high-linearity 10KV anti-EMC high-isolation transmission and I/V conversion between industrial field sensors and instrumentation, PLC and DCS. Products include IC PCB package and DIN35 Rail-mounted packaging, It is widely used in track voltage monitoring, generator or motor safe operation monitoring, power transmission and distribution remote monitoring, instrumentation and sensor signal transceiver, medical equipment safety barrier, industrial automation control, nuclear power equipment etc other fields.