4-20mA Loop Isolator | HART Pass-Through Signal Conditioner | 2-Wire Passive Signal Isolator | Signal Distributor

2-Wire Passive 4-20mA Loop Isolation HART Transmission Conditioner: ISO 4-20mA-EHT

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We accept OEM customization as well as ODM development, design and manufacturing services.

Product Features：

● Exclusive patented power-feeding technology for signal loop, no external operating power supply required

● 3000VDC galvanic isolation between input and output of 4–20mA loop signals

● Equipped with HART pass-through function to support bidirectional transmission of HART signals

● While isolating 4–20mA input and output, it enables bidirectional transmission of HART protocol signals as well as measurement and control via handheld communicators

● Ultra-wide input voltage range (5 ~ 32V) for active 4–20mA signal acquisition

● Loop-powered output design eliminates conflicts between circuits powered by different power sources

● Active signal input and passive output to control active loads in current loops

● Ultra-high accuracy and linearity across full measuring range with non-linearity error < 0.2%

● Industrial operating temperature range: -40 ~ +85 ℃

● Compact standard SIP 12-pin package with UL94V-0 flame retardant rating

Typical Applications：

● Delivers dedicated HART signal transmission channels to fully leverage dual advantages of digital and analog signals

● Bidirectional HART signal transmission facilitates communication between field smart sensors/instruments and control room DCS distributed control systems

● Signal matching and control for 2-wire active loads

● Isolation conditioning and transmission for 4–20mA sensor signal acquisition

● Signal isolation between PLC and DCS input channels to prevent cross-talk interference

● Isolation and suppression of ground loop circulating current interference

● Isolation safety barriers for power instruments and medical equipment monitoring

● Realization of single-in single-out, dual-in dual-out and multi-channel isolation transmission conversion for 4–20mA current signals 

Overview：

The ISO 4-20mA-EHT series HART pass-through 4–20mA 2-wire passive isolation conditioner is a dedicated signal isolation, conditioning and conversion module designed for industrial instruments, smart sensors and transmitters with HART protocol transmission and control capabilities. It converts incoming active 4–20mA current signals into isolated passive control signal outputs to drive explosion-proof 2-wire powered 4–20mA current loops. The module matches sensor signal acquisition circuits with active loads on analog input interfaces, and effectively resolves power supply conflicts between active 4–20mA signal acquisition loops and separate 2-wire current loop power circuits.

Combining the strengths of signal isolation conditioning and HART communication technology, this product delivers isolated signal conversion and accurate online measurement & control between 2-wire field sensors, instruments and transmitters. It finds extensive applications in smart sensors, intelligent control instruments and transmitters, industrial intelligent control systems, safety isolation barriers for power and medical equipment, industrial robots, chemical fuel facilities and nuclear power safety equipment.

The ISO 4-20mA-EHT module is primarily deployed for isolation conditioning of 4–20mA signals and transparent transmission of HART signals from field smart sensors. Adopting high-efficiency patented loop power harvesting technology, its 2-wire loop-powered output eliminates the need for an independent power supply, removing two power wires and simplifying electrical design while cutting on-site wiring costs for users. Equipped with advanced digital circuitry and galvanic isolation technology, the module isolates input and output 4–20mA analog signals while enabling bidirectional HART protocol communication.

The output stage of ISO 4-20mA-EHT is engineered for 2-wire supply loops where 24VDC power sources are connected in series with sampling resistors (for 2-wire instruments). It is compatible with analog input ports carrying active loads, such as widely used upper computer analog input boards, PLCs, DCS and other industrial instruments. Its extremely low equivalent input resistance captures signal voltages from sensor output loops across an ultra-wide range of 5–32VDC, enabling long-distance, distortion-free signal transmission without external auxiliary power supplies.

Internally integrated circuits include isolated HART digital signal transmission circuitry, active-to-passive 4–20mA isolation conditioning circuitry, and bidirectional isolated HART communication circuits. It supports data exchange between field smart sensors & equipment and control-room DCS distributed control systems, fully unlocking the combined benefits of digital and analog signaling. Operation is highly user-friendly: only an external 2kΩ multi-turn potentiometer is required for ADJ calibration to complete isolation, transmission, acquisition and control of 2-wire 4–20mA signals.

Advanced internal integration processes and innovative isolation techniques deliver a 3000VDC isolation rating, enabling stable operation under harsh industrial conditions with wide temperature swings, high humidity and vibration. Two mounting options are available: surface-mount IC packaging for PCB soldering, and standard DIN35 rail mounting. The rail-mounted variant supports single-in single-out, dual-in dual-out and multi-channel isolated signal conversion, allowing flexible configuration to match field site requirements.

Absolute Maximum Ratings：

(Continuous operation under absolute maximum rating conditions will shorten service life; exceeding any rating will cause irreversible permanent damage to the product.)

Continuous Isolation Voltage: 3000 Vrms

Maximum Input Voltage: 36 VDC

Operating Temperature: -40 ~ +85℃

Soldering Temperature: +300℃ 

General Specifications

Accuracy & Linearity Error Class: 0.2 grade; 0.5 grade

Auxiliary Power Supply: None

Operating Temperature: -40 ~ +85℃

Operating Humidity: 10 ~ 90% (Non-condensing)

Storage Temperature: -45 ~ +105℃

Storage Humidity: 10 ~ 95% (Non-condensing)

Load Regulation: ＜0.05% of measured value per 100Ω

Isolation: Dual galvanic isolation between signal input and signal output

Response Time: ≤100 ms

Dielectric Withstand Voltage: 3 kV (60 Hz, 1 min), leakage current ＜1 mA

Rated Impulse Withstand Voltage: 3 kV peak, 1.2/50 μs waveform

Temperature Drift: 0.0050% F.S./℃ (within -40℃ ~ +85℃ operating range)

Technical Specifications：

Functional Block Diagram and Pin Definition of SIP12 Package IC Module：

Pin Function Description (Single In-line Package: SIP12 Pin)：

Outline Dimensions & Typical Application Diagram of IC Module：

Outline Dimensions and Typical Application Diagram of DIN3 Compact Low-Cost DIN Rail Mounted Product：

The DIN3 ISO 4-20mA-EHT is a compact, low-cost DIN rail-mounted HART transparent transmission 4-20mA two-wire passive isolation conditioner.

It features an ultra-thin, miniaturized design with no external components required. Compatible with the universal industrial standard 35 mm DIN rail mounting groove, the device only needs wiring on terminals at both sides to simultaneously realize isolation, conditioning conversion of single-channel two-wire 4-20mA signals as well as HART transparent transmission function.

Outline Dimensions and Pin Function Description for DIN35 Rail Mounted Products(* The product LOGO and model number are printed on the housing)

Shenzhen Zhikongquan Technology Co., Ltd.：Drawing on 28 years of profound industry experience and accumulated resources, we focus on sectors including industrial automation, sensors, industrial instruments, and robotics. We have integrated manufacturing resources from over a thousand manufacturers. We are committed to promoting Made in China and Created in China to the world, delivering high-quality, cost-effective Chinese products to manufacturing enterprises across the globe. only a selection of our products is listed on our catalog; feel free to contact us for more product information anytime.

ddress: Room 1501, Global Logistics Center, No.1 Huanan Avenue, Pinghu Sub-district, Longgang District, Shenzhen City, Guangdong Province, P.R.China

Contact Person: Mulan.Liu

Title: Operations Director

Email: info@zgznh.com

          sales1@zgznh.com

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