STMicroelectronics ISO808QTR-1

Overview

ISO808QTR-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 ISO808QTR-1 datasheet, ISO808QTR-1 pinout, ISO808QTR-1 application, or ISO808QTR-1 equivalent, key selection considerations include its TFQFPN32 package with 32-pin isolation barrier layout, synchronous/direct control interface modes, per-channel thermal shutdown (T_JSD = 150–200 °C), common open-drain FAULT reporting, and compliance with IEC 61000-4-x immunity and UL1577/UL508 safety standards.

Technical Context

The ISO808QTR-1 implements a two-die architecture with physically separated Logic Stage (VDD/GNDDD) and Process Stage (VCC/GNDCC), linked via capacitive isolation. Its Synchronous Control Mode (SCM) uses independent LOAD and SYNC pins to coordinate multi-device output transitions with ≤6 μs jitter, while Direct Control Mode (DCM) enables immediate INx-to-OUTx mapping when SYNC and LOAD are tied.

Protection is implemented at multiple levels: per-channel overtemperature (OVT) with thermal independence, case-level overtemperature (OVC), short-circuit current limiting (I_LIM(MIN) = 1 A), VCC clamping (47–57 V), and loss-of-GND/VCC detection. The FAULT pin aggregates OVT events and internal communication errors as an OR-wired active-low open drain signal.

Key Specifications

Pinout & Package

ISO808QTR-1 is housed in a TFQFPN32 (5 mm × 5 mm, 0.5 mm pitch) thermally enhanced package with exposed die pad connected to GND_CC. The pinout separates logic-side (VDD, GNDDD, IN1–IN8, LOAD, SYNC, OUT_EN, FAULT) and process-side (VCC, GND_CC, OUT1–OUT8) terminals to maintain ≥3.3 mm creepage/clearance across the isolation barrier.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STISO808TR, ISO808QTR-1 trades thermal margin for compactness and board area savings; versus ISO1H808DWR, it delivers superior timing determinism, higher current capability, and granular thermal fault isolation essential for mission-critical industrial control.

Availability

ISO808QTR-1 is available at Aetrix Electronics and suitable for programmable logic controllers, industrial PC peripheral I/O, and numerical control machines requiring stable component supply, long-term lifecycle support, and certified galvanic isolation.

Supply support for ISO808QTR-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 automotive, industrial, and power discrete solutions with strong IP in isolation technology and smart power integration.

The ISO808 family belongs to ST's industrial-grade isolated driver product line, engineered specifically for high-reliability programmable logic control and factory automation where functional safety, thermal robustness, and EMI resilience are mandatory.

FAQ

What is the maximum continuous output current per channel for ISO808QTR-1?

The ISO808QTR-1 supports up to 1 A continuous output current per channel, as specified by its I_LIM(MIN) = 1 A short-circuit current limit and thermal design enabling sustained operation at 1 A with proper PCB copper pour and ambient temperature ≤85 °C. Derating applies above 85 °C ambient per the TFQFPN32 thermal data (R_{th j-amb} = 25 °C/W).

How does the Synchronous Control Mode (SCM) reduce output jitter?

SCM reduces jitter by decoupling input latching (LOAD) from output update (SYNC), allowing precise timing of the transmission buffer update across all eight channels. With t_jitter(SCM) ≤ 6 μs, synchronized updates across multiple ISO808QTR-1 devices eliminate cumulative skew - critical for coordinated motion control or multi-axis enable signals in CNC systems.

Can ISO808QTR-1 drive inductive loads without external flyback components?

Yes. Its integrated fast demagnetization circuit achieves V_DEMAG = V_CC − 54 V (TYP), clamping flyback voltage well below destructive levels for typical 24 V inductive loads. This eliminates the need for external flyback diodes or RC snubbers in most solenoid, relay, and valve applications, simplifying layout and improving reliability.

What safety certifications apply to ISO808QTR-1?

ISO808QTR-1 holds UL1577 (3000 V_RMS/1 s production test), UL508 (industrial control equipment), and complies with IEC 60747-17 (formerly VDE 0884-11) for reinforced galvanic isolation. It also meets immunity standards IEC 61000-4-2 (ESD), -4-4 (EFT), -4-5 (surge), and -4-8 (power frequency magnetic field), making it suitable for CE-marked industrial equipment.