STMicroelectronics ISO808TR-1

Overview

ISO808TR-1 from STMicroelectronics is a galvanically isolated octal high-side power solid-state relay designed for driving high inductive loads in industrial control systems. It features dual isolated voltage domains (VCC = 9.2–36 V, VDD = 2.75–5.5 V), per-channel R_DS(on) = 0.125 Ω (TYP), I_OUT < 1 A, and fast demagnetization (V_DEMAG = V_CC − 54 V) to suppress inductive kickback in PLC output stages.

For engineers reviewing the ISO808TR-1 datasheet, ISO808TR-1 pinout, ISO808TR-1 application, or ISO808TR-1 equivalent, this device supports synchronous/direct control modes, offers per-channel thermal shutdown (T_JSD = 150–200 °C), common fault reporting via open-drain FAULT pin, and meets IEC 61000-4-x immunity standards - critical for robust I/O module design in harsh environments.

Technical Context

The ISO808TR-1 implements a two-chip architecture with galvanic isolation between logic (VDD/GNDDD) and process (VCC/GNDCC) domains, enabling independent supply domains and safety-rated insulation (1500 V_PEAK, 2500 V_RMS). Its internal watchdog (t_WD = 272–400 μs) ensures safe output disable during host MCU freeze or logic-side supply loss.

It supports two operational modes: Direct Control Mode (DCM), where INx directly drives OUTx when SYNC/LOAD are tied low; and Synchronous Control Mode (SCM), where LOAD latches inputs and SYNC triggers simultaneous output update - reducing channel-to-channel jitter to ≤6 μs and enabling synchronized multi-device operation.

Key Specifications

Pinout & Package

ISO808TR-1 is supplied in PowerSO-36 package with exposed VCC-connected tab for thermal management. Pin assignment follows ST's standardized layout for galvanically isolated drivers, with dedicated logic (IN1–IN8, VDD, GNDDD) and process-side (OUT1–OUT8, VCC, GNDCC) terminals separated by ≥2.6 mm creepage/clearance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar galvanically isolated high-side driver applications.

Compared with ISO808-1, ISO808TR-1 adds traceability and packaging consistency for volume manufacturing; versus ISO808Q-1, it trades compactness for higher isolation voltage and thermal robustness - making it optimal for DIN-rail mounted PLC modules requiring long-term reliability.

Availability

ISO808TR-1 is available at Aetrix Electronics and suitable for programmable logic controller output modules, industrial PC peripheral I/O cards, and numerical control machine interfaces requiring stable component supply, full industrial qualification, and tape-and-reel logistics support.

Supply support for ISO808TR-1 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, specializing in power management, analog, microcontrollers, and automotive-grade ICs with vertical manufacturing capabilities.

The ISO808 family belongs to ST's industrial isolated driver product line, engineered specifically for replacing electromechanical relays in high-reliability programmable controllers and factory automation systems - emphasizing safety certification, thermal resilience, and deterministic timing.

FAQ

What is the maximum continuous output current per channel for ISO808TR-1?

The ISO808TR-1 supports up to 1 A continuous output current per channel, enforced by internal short-circuit protection with ILIM(MIN) = 1 A. This limit holds across the full operating temperature range (−40 °C to 125 °C) and is independent of other channels' states due to thermal independence design.

How does the FAULT pin behave during a communication error between logic and process sides?

On internal communication error - such as data corruption during isolation barrier transmission - the FAULT pin asserts low immediately. Outputs retain their prior state briefly, then turn off within one refresh cycle (≤400 μs). The FAULT signal remains active until the error condition clears and a valid transmission completes.

Can ISO808TR-1 operate with 3.3 V logic supply while driving 24 V loads?

Yes. ISO808TR-1 accepts VDD = 2.75–5.5 V, fully supporting 3.3 V TTL/CMOS logic levels. Its galvanic isolation allows simultaneous 3.3 V digital control (INx, SYNC, LOAD) and 24 V process-side switching (VCC = 24 V, OUTx → load → GNDCC), with VIH = 0.7×VDD and VIL = 0.3×VDD thresholds ensuring noise margin.

What is the purpose of the exposed VCC-connected tab in the PowerSO-36 package?

The exposed tab (Pin 36) is internally bonded to VCC and serves dual functions: thermal conduction path to the PCB heatsink (R_th(j-case) = 0.8 °C/W), and structural anchor for high-current routing. It must be soldered to a large copper pour connected to the VCC net - not left floating - to ensure both thermal stability and isolation barrier integrity.