ST’s Latest Transceivers Boost Industrial Automation

STMicroelectronics has introduced the ST4E1240 RS-485 transceiver. Specifically, it comes with 40Mbit/s speed, PROFIBUS-compatible output, and transient and hot-swap protection.

The ST4E1240 is the first in a new family of transceivers from ST featured to deliver robust and reliable RS-485 signaling. This makes suitable for modern, performance-hungry industrial applications.

Moreover, he new transceivers support data speeds far above the original RS-485 standards and allow multipoint connections over extended cable runs with more than 64 transceivers on the bus. Typical uses are in programmable logic controllers (PLCs), robots, telecom infrastructures, smart-building controls, and servo drives. In addition, the transceivers work well too with optical networking devices, grid infrastructure, and data-acquisition systems including smart meters and backplane buses.

Features, Specifications

The protection built into the ST4E1240 meets IEC 61000-4-2 up to +/-12kV contact discharge. Thus, allowing the use of devices without external ESD protection. There is also class-A fast-transient protection up to +/- 4kV, meeting IEC 61000-4-4, ensuring data integrity and bus stability.

Hot-swap circuitry prevents unwanted states on the bus during device switch-on or plug-in. Moreover, it is capable of discharging up to 100pF parasitic capacitance.

Furthermore, the transceiver integrates failsafe protection that drives the output high to avoid an indeterminate state upon detecting an open, shorted, or idle bus. Other features include 250mA short-circuit protection and thermal shutdown.

The ST4E1240 fulfils all TIA/EIA-485 (RS-485) standards. Also, it ensures the output differential voltage exceeds 2.1V, at 5V supply, for compatibility with the popular PROFIBUS field bus standard. There is also a shutdown mode, controlled with external enable pins. Specifically, these reduce the quiescent current below 3.5µA for use in energy-conscious applications.

 The ST4E1240 RS-485 transceiver is part of ST’s 10-year longevity program that ensures long-term product support. The devices are in production now and available in the SO-8 4.9mm x 3.91mm package.