STMicroelectronics ISO808TR

Overview

ISO808TR 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), fast demagnetization (V_DEMAG = VCC − 54 V), and integrated short-circuit/over-temperature protection with thermal independence per channel.

For engineers reviewing the ISO808TR datasheet, ISO808TR pinout, ISO808TR application, or ISO808TR equivalent, this device supports precise timing-critical PLC I/O, synchronized multi-device output control via SYNC/LOAD, fault diagnostics via open-drain FAULT, and safe operation under IEC 61000-4-x immunity and UL1577/UL508 certification requirements.

Technical Context

The ISO808TR implements a two-chip architecture with galvanic isolation between logic (VDD/GNDDD) and process (VCC/GNDCC) domains, enabling independent supply and fault containment. Its synchronous control mode (SCM) uses separate LOAD and SYNC signals to minimize output jitter (≤6 μs) and enable simultaneous switching across multiple devices.

Protection is implemented at three levels: per-channel junction over-temperature shutdown (T_JSD = 150–200 °C), case over-temperature (T_CSD = 125–135 °C), and active current limiting (ILIM = 0.7 A for ISO808/ISO808Q, 1 A for ISO808-1/ISO808Q-1). Fault reporting combines OR-wired OVT and internal communication error detection on a single open-drain FAULT pin.

Key Specifications

Pinout & Package

ISO808TR is available in PowerSO-36 package with exposed VCC-connected tab for enhanced thermal performance (R_{th j-case} = 0.8 °C/W). Pin functions are validated per DS14169 Rev 6, Figure 2 and Table 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISO808TR, STISO808QTR trades thermal robustness for compactness, while ISO1H813DWR sacrifices synchronization precision and channel-level fault isolation for lower unit cost - making ISO808TR optimal for safety- and timing-critical industrial control.

Availability

ISO808TR is available at Aetrix Electronics and suitable for programmable logic controllers, industrial PC peripheral I/O, and numerical control machine tool applications requiring stable component supply, long-term lifecycle support, and certified galvanic isolation.

Supply support for ISO808TR 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 management solutions with vertical manufacturing capabilities and broad IP portfolio.

The ISO808 family belongs to ST's industrial isolated drivers product line, engineered specifically for high-reliability, high-noise industrial automation systems requiring reinforced insulation, multi-level protection, and deterministic timing control.

FAQ

What is the difference between ISO808TR and ISO808-1TR?

The ISO808TR corresponds to the base ISO808 variant with 0.7 A per-channel current limit (ILIM), while ISO808-1TR supports 1 A per channel. Both share identical pinout, isolation rating, and protection features. The -1 suffix denotes higher current capability enabled by internal current-sense threshold adjustment - verified in DS14169 Table 6.

Can ISO808TR drive inductive loads above 1 H?

Yes - ISO808TR is explicitly characterized for high inductive loads, with V_DEMAG = VCC − 54 V ensuring safe energy dissipation. Its fast demagnetization capability and integrated overvoltage clamping (VCC clamp = 47–57 V) protect against flyback spikes from loads ≥1 H when properly decoupled with snubbers per application note AN5095.

How does the FAULT pin behave during a single-channel over-temperature event?

FAULT asserts low immediately upon detection of any per-channel junction over-temperature (TJ > TJSD) or case over-temperature (TC > TCSD). It remains asserted until all triggered faults clear and junction/case temperatures fall below respective reset thresholds (TJR or TCR), as confirmed in DS14169 Section 6.4 and Table 6.

Is external pull-up required on the FAULT pin?

Yes - FAULT is an open-drain output requiring an external pull-up resistor (typically 4.7 kΩ to VDD) to generate a valid logic-high level. Without it, the pin floats and cannot indicate normal operation; this is specified in DS14169 Table 6 and Figure 20, and verified on ST evaluation boards like STEVAL-IHM038V1.