PWM to 4-20mA Two-Wire Passive Isolated Transmitter IC

Device features:

1. Protect the control loop of the upper stage of the host computer.

2. Reduce the impact of environmental noise on the test circuit, and can overcome inverter noise and various high and low frequency pulsation interference.

3. It suppresses the interference of circulating currents in public ground wires and pulses of frequency converters, solenoid valves, thyristors, etc. to equipment. It also has the function of limiting voltage and current for lower-level equipment. It is a faithful protection for transmitters, instruments, frequency converters, solenoid valves, PLC/DCS input and output, and communication interfaces.

The DIN35 series standard 35mm guide rail card holder structure is easy to install and can effectively isolate: the potential difference between signal input, signal output, power supply and earth.

Product Advantage

1. The ISO D-O1 converts PWM pulse-width signals directly into standard 4-20mA current loop output without any external power supply — power is drawn exclusively from the output current loop via Sunyuan's patented back-end feeding technology. The output loop supply voltage range spans 12–36VDC with power consumption of just 0.15W at 20mA, making it ideal for bus-powered remote I/O modules and battery-backed field installations. Input accepts PWM signals from 10Hz to 50KHz across five selectable frequency bands with 0–100% duty cycle and input levels from 3.3V to 24V. The internal architecture integrates high-speed isolation coupling, precision reference voltage switching control, low-pass filtering, drive amplification, and VI conversion — all in a single SIP8 IC measuring just 22×11×9mm. This eliminates the need for separate power supplies, DAC modules, and discrete isolation circuits in PWM-driven process control applications.

2. Signal input and output are galvanically isolated at 3,000VDC with insulation resistance exceeding 100MΩ at 500VDC and leakage current below 1mA at 60Hz. The module also withstands 3KV peak impulse surges at 1.2/50μs. The high-speed photocoupler isolation architecture paired with precision analog signal conditioning delivers noise-immune PWM-to-current conversion that suppresses ground loops, common-mode interference, and high-frequency spatial EMI — critical when microcontroller PWM outputs share ground references with industrial power circuits. This isolation grade is certified for deployment in power equipment monitoring, medical device safety barriers, and petrochemical hazardous-area signal conditioning where electrical separation between digital control and analog field loops is a regulatory requirement.

3. Available in 0.1, 0.2, and 0.5 accuracy grades, the ISO D-O1 delivers nonlinearity below 0.2% full scale with load regulation under 0.05% per 100Ω change. Temperature drift holds at 100 ppm/°C with a coefficient of 0.0050% F.S./°C across the -40°C to +85°C operating range. Five factory-calibrated frequency models cover the full spectrum: D1 (10–99Hz for slow electromechanical control), D2 (100Hz–0.9KHz), D3 (1–9KHz for standard MCU PWM peripherals), D4 (10–19KHz), and D5 (20–50KHz for high-resolution converters) — plus D8 for custom frequency ranges. Output ripple is held to just 10–20mV RMS unfiltered, and response time ranges from 0.1 to 1 second, preserving the dynamic tracking of PWM duty cycle changes while filtering high-frequency carrier components for clean 4-20mA output.

4. At just 22×11×9mm in a SIP8 pin package with UL94V-0 flame-retardant encapsulation and +300°C lead temperature tolerance, the ISO D-O1 integrates directly into microcontroller boards, PLC analog output modules, and embedded DA converter circuits — replacing discrete optocouplers, reference voltage sources, low-pass filters, and VI converters that would occupy 5–10× the PCB area. For cabinet-level deployment, the same core technology is available in DIN3 ultra-compact single-channel rail-mount (12.5mm thickness), DIN35 multi-channel 1×1/2×2/3×3 rail-mount platforms with built-in surge protection, and PIM panel-mount intelligent display transmitters with dual-channel alarm relay outputs and programmable setpoints — covering every deployment scenario from embedded DAQ boards to operator-facing panel displays.

5.The module connects directly between any microcontroller PWM output and a standard 4-20mA current loop without external components, configuration, or calibration. Input impedance is 1kΩ, compatible with all common MCU GPIO drive strengths. The 4-20mA output drives loads from 0–750Ω at 20mA, sufficient for PLC analog input cards, DCS modules, variable frequency drives, and process controllers. This makes the ISO D-O1 the simplest bridge between digital control systems and analog field instrumentation — one module replaces the traditional chain of PWM DAC, voltage-to-current converter, and signal isolator. Designers can dedicate a single MCU timer output to create a fully isolated, loop-powered industrial 4-20mA channel with zero additional analog design effort.

6. With over 3,300 product views, the ISO D-O1 serves applications spanning PLC and VFD control interfacing, industrial boiler temperature auto-selection control, PWM-based DA conversion, process control and automation equipment, and multi-channel PWM-to-4-20mA conversion (1-in-1-out through 3-in-3-out). The PIM panel-mount intelligent transmitter variant adds dual isolated alarm outputs (OC open-collector, 120mA drive capability), programmable setpoints with positive/negative alarm direction, adjustable damping (0–20s), and a 4-digit LE

Technical Parameters

Product Uses

Here are seven specific application scenarios of the ISO D-O Series Two-Wire Passive PWM-to-Analog Signal Isolation Transmitter IC:

1.Metallurgy and mining: The transmitter is used to convert PWM control signals from industrial controllers into isolated 4-20mA analog signals for driving actuators and monitoring equipment in metallurgical furnaces and mining machinery, with 3000VDC isolation protecting control systems from high-power electrical interference in harsh industrial environments.

2.Petrochemical processing: The transmitter is used to isolate and convert PWM signals from DCS/PLC systems into standard 4-20mA current signals for controlling valves, pumps, and heaters in refineries and chemical plants, with the passive two-wire design eliminating the need for power supply wiring in hazardous explosion-proof areas.

3.Power equipment: The transmitter is used to convert PWM modulation signals into analog current signals for motor voltage regulation, generator excitation control, and power distribution equipment monitoring, with high-speed optoelectronic isolation ensuring accurate signal conversion and electrical safety between high-voltage and low-voltage circuits.

4.Medical instruments: The transmitter is used to isolate PWM signals from microprocessor-controlled medical equipment and convert them to precision analog signals for driving actuators in diagnostic and therapeutic devices, with 3000VDC isolation providing patient safety barriers and the ultra-compact SIP8 package enabling integration into space-constrained medical instrument designs.

5.Industrial automation: The transmitter is used to interface PWM-output controllers with standard analog input modules in PLC, DCS, and FCS systems, converting pulse-width modulated signals into 4-20mA current loops for controlling motors, conveyors, and robotic actuators on automated production lines without requiring external power supply.

6.New energy facilities: The transmitter is used to convert PWM signals from solar inverter controllers, wind turbine pitch systems, and battery management systems into isolated analog signals for monitoring and control, with wide operating voltage range (12-36VDC) and industrial-grade temperature tolerance suiting outdoor renewable energy installations.

7.Military and scientific research: The transmitter is used to provide isolated PWM-to-analog signal conversion in military equipment control systems and scientific research instruments, with the compact PCB-mount design, high conversion precision, and 3000VDC isolation meeting the stringent reliability and safety requirements of defense and laboratory applications.