Isolated RS-485 differential bus transceivers deliver high voltage, low EMI for IIoT

Intersil, a subsidiary of Renesas Electronics Corporation, today announced two new high-speed, isolated RS-485 differential bus transceivers that provide 40Mbps bidirectional data communication for Industrial Internet of Things (IIoT) networks. The ISL32741E offers 1,000V_RMS working voltage and 6kV of reinforced isolation, more than 2x higher than competitive solutions. The higher working voltage and reinforced isolation is required for today’s most rigorous medical and high-speed motor control applications. The ISL32740E with 2.5kV of isolation and 600V_RMS working voltage comes in the industry’s smallest package, enabling high channel density for programmable logic controllers (PLCs) in factory automation applications.

The ISL3274xE transceivers provide additional advantages over other isolation technologies, including ultra-low radiated emission and EMI susceptibility, support for up to 160 devices on the bus, and an extended 125°C temperature range. These devices leverage giant magnetoresistance (GMR) technology that provides galvanic isolation to keep the communication bus free from common-mode noise generated in electrically noisy factory and building automation environments. In addition, Intersil’s GMR isolation does not require the elaborate encoding schemes found in capacitive and transformer-based isolators that use RF carriers or pulse-width modulation (PWM) to transfer DC and low-frequency signals across the barrier.

The ISL3274xE transceivers are ideally suited for the equipment-to-bus interface in PROFIBUS DP and high-speed RS-485 networks that connect PLCs to instruments, robots, motor control drives, as well as data acquisition and digital I/O modules. In addition to not requiring any shielding, these transceivers simplify PCB layout, use less board space, and enhance data transmission reliability and integrity. The ISL3274xE devices also offer low power consumption. For example, the ISL32740EIAZ’s 60mA supply current allows it to operate in a tiny 4mm x 5mm QSOP package at maximum speed without overheating.

On the non-isolated control-side, the ISL3274xE transceivers support direct connection to a 3V microcontroller (MCU) while the isolated bus-side connects to a higher voltage 5V supply for communication of strong bus signals across 100 meters and longer distances. The ISL3274xE transceivers are fully compliant with the EN 50081 and EN 50082-2 electromagnetic compatibility (EMC) standards and the umbrella line-voltage standard for information technology equipment (ITE) EN 61000.

“Our latest high-speed RS-485 isolated transceivers radiate virtually no EMI, and they eliminate ground loops between bus nodes to protect data transmission,” said Philip Chesley, vice president of Industrial Analog and Power products at Intersil. “The ISL32741E’s high working voltage and ability to push its reinforced isolation barrier up to 6kV enables customers to solve their most difficult IIoT networking design problems.

Key Features and Specifications of ISL32741E and ISL32740E Family

·        40Mbps data rate enables high-speed data transmission

·        Supports 3V to 5V power supplies

·        Offers 5ns pulse skew and 20ns propagation delay

·        The ISL32741E offers 6kV_RMS isolation/1,000V_RMS working voltage, and 12.8kV surge immunity

·        The ISL32740E offers 2.5kV_RMS isolation/600V_RMS working voltage

·        Single unit load allows up to 160 devices on the bus

·        50kV/µs (typ), 30kV/µs (min) common-mode transient immunity provides reliable data transmission in noisy environments

·        Offers a barrier lifetime of 44,000 years

·        15kV ESD bus-pin protection, and low EMC footprint

·        Thermal shutdown protection prevents damage during bus contention or excessive current

·        PROFIBUS compliant

The ISL3274xE can be combined with the ISL28025 precision digital power monitor, ISL12022M low power real time clock, and Renesas MCUs to create a system solution.

The ISL32740E and ISL32741E 40Mbps RS-485 transceivers are available now with prices ranging from USD$3.79 to USD$4.79 depending on package type and temperature range. Evaluation boards are available for $99 USD.