STMicroelectronics ST485ERBN

Overview

ST485ERBN from STMicroelectronics is a half-duplex, ±15 kV HBM ESD-protected RS-485/RS-422 transceiver in SO8 package, featuring 300 µA quiescent current, 2.5 Mbps max data rate, -7 V to +12 V common-mode input range, and thermal shutdown protection. It integrates one driver and one receiver for multipoint bus communication in industrial automation and building control systems.

For engineers reviewing the ST485ERBN datasheet, ST485ERBN pinout, ST485ERBN application, or ST485ERBN equivalent, key selection criteria include ESD robustness (±15 kV HBM), low-power operation (300 µA typ.), bus node count support (64 transceivers), and SO8-compatible layout integration for space-constrained RS-485 nodes.

Technical Context

The ST485ERBN implements a fail-safe receiver with 70 mV typical hysteresis and differential threshold of ±0.2 V across -7 V to +12 V common-mode range, enabling reliable signal detection in noisy industrial environments. Its driver uses current-limiting and thermal shutdown to prevent latch-up during bus faults.

Control logic follows standard RS-485 enable conventions: RE and DE are active-low and active-high respectively, allowing independent receiver/driver gating. Propagation delay is 30 ns (typ.) with 5 ns skew, supporting timing-critical 2.5 Mbps half-duplex links without external timing compensation.

Key Specifications

Pinout & Package

ST485ERBN is housed in an SO8 (Small Outline 8-pin) package with 1.27 mm pitch, ECOPACK®-compliant lead-free finish, and standard tape-and-reel packaging (2500 units/reel).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RS-485 transceiver applications.

Compared with MAX485ESA+ and SN65HVD72DR, ST485ERBN uniquely balances 5 V operation, ultra-low 300 µA supply current, ±15 kV ESD, and thermal fault protection-making it optimal for battery-powered or field-serviceable industrial nodes where reliability and power budget are co-constrained.

Availability

ST485ERBN is available at Aetrix Electronics and suitable for industrial PLC I/O modules, smart energy meters, and building automation controllers requiring stable component supply and long-term production continuity.

Supply support for ST485ERBN includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, delivering intelligent power, sensing, and connectivity solutions for automotive, industrial, and consumer markets.

The ST485ERBN belongs to ST's RS-485 transceiver product line, engineered specifically for robust, low-power, multi-node industrial communications in harsh electrical environments with stringent ESD and thermal reliability requirements.

FAQ

Does ST485ERBN support full-duplex RS-422 operation?

No. ST485ERBN is a half-duplex transceiver with shared A/B bus terminals and separate RE/DE control lines. It lacks independent transmit and receive differential pairs required for true full-duplex RS-422. Its design targets RS-485 multidrop bus topologies where bidirectional communication occurs on the same pair.

What is the minimum load resistance required for compliant RS-485 driver output?

The ST485ERBN driver meets RS-485 specifications with a minimum load of 27 Ω differential (representing 32 unit loads). Its output voltage remains ≥1.5 V under this load, satisfying the RS-485 standard's 1.5 V minimum differential output requirement at maximum data rates.

Can ST485ERBN be used with 3.3 V microcontrollers?

Yes, but only for logic-level interfacing (DI, RE, DE, RO pins). These inputs/outputs are 5 V tolerant and compatible with 3.3 V CMOS levels. However, VCC must be supplied with 5 V; the device does not operate from 3.3 V. Level-shifting is unnecessary for control signals, simplifying interface design.

How does the thermal shutdown mechanism affect bus communication during overload?

When driver output current exceeds safe limits, thermal shutdown activates within milliseconds, forcing A and B outputs into high-impedance state. This preserves device integrity and prevents bus contention, but halts transmission until temperature normalizes. Recovery is automatic upon cooling, with no latch-up or manual reset required.