STMicroelectronics ISO8200AQ

Overview

ISO8200AQ from STMicroelectronics is a galvanically isolated octal high-side smart power solid-state relay with SPI interface, designed for driving resistive, capacitive, and inductive loads referenced to ground. It features 8 independent high-side switches, 10.5–45 V VCC operation, 0.12 Ω R_DS(ON) per channel at 25 °C, 20 MHz SPI daisy-chain capability, and integrated per-channel overtemperature and short-circuit protection - deployed in industrial PLC I/O modules and CNC machine control systems.

For engineers reviewing the ISO8200AQ datasheet, ISO8200AQ pinout, ISO8200AQ application, or ISO8200AQ equivalent, key selection criteria include galvanic isolation rating (937 V_PEAK working voltage), per-channel thermal independence, fast demagnetization (V_DEMAG(TYP) = V_CC − 50 V), fault diagnostics via open-drain FAULT/PGOOD pins, and compatibility with 3.3 V/5 V MCU logic levels.

Technical Context

The ISO8200AQ implements dual isolated voltage domains: V_CC/GND_CC powers the process stage (high-side drivers), while V_DD/GNDDD supplies the control logic stage. Communication across the isolation barrier uses ST's proprietary protocol, not standard SPI signaling - the external SPI interface (SS, CLK, SDI, SDO) only connects to the logic side; internal data transfer to the process stage occurs asynchronously and is protected by a watchdog timer (t_WD = 272–400 μs).

Each channel integrates active current limiting (I_LIM = 0.7–1.9 A), junction- and case-level thermal shutdown (T_JSD = 150–170 °C; T_CSD = 115–145 °C), loss-of-ground detection, V_CC/V_DD UVLO with hysteresis, and V_CC clamping (45–52 V). Fault reporting is per-channel via an 8-bit Fault Register, with OR-wired active-low FAULT output indicating any OVT, SPI error, or communication failure.

Key Specifications

Pinout & Package

ISO8200AQ is housed in a TFQFPN32 (5 × 5 mm, 0.5 mm pitch) package with dual exposed thermal pads: TAB(V_CC) internally connected to V_CC, and TAB(GND_CC) to GND_CC. The 32-pin layout separates logic-side (V_DD, GNDDD, SPI) and process-side (V_CC, GND_CC, OUT1–OUT8) terminals to maintain creepage/clearance ≥3.3 mm across the isolation barrier.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL7407LPWR and ADUM3050CRZ, ISO8200AQ uniquely integrates galvanic isolation, 8-channel high-side switching, per-channel thermal/current protection, and SPI diagnostics in a single TFQFPN32 package - reducing component count by ≥12 devices and eliminating design risk from external fault-handling logic.

Availability

ISO8200AQ is available at Aetrix Electronics and suitable for programmable logic control, industrial PC peripheral I/O, and numerical control machines requiring stable component supply under extended temperature and high-reliability conditions.

Supply support for ISO8200AQ 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, specializing in automotive, industrial, and power management ICs with vertical manufacturing and rigorous AEC-Q and IEC qualification programs.

The ISO8200AQ belongs to ST's industrial smart-power portfolio, engineered specifically for high-density, safety-certified digital output modules in harsh electromagnetic environments - emphasizing galvanic isolation integrity, diagnostic completeness, and long-term parametric stability.

FAQ

What is the maximum continuous output current per channel, and how is it enforced?

The ISO8200AQ limits continuous output current to ≤0.7 A per channel via active current regulation. When sensed current exceeds the threshold (0.7–1.9 A depending on V_CC and temperature), the internal gate driver modulates the output FET's conduction to clamp I_OUT. This is distinct from thermal shutdown - current limiting operates continuously under overload, while OVT protection triggers only above 150–170 °C junction temperature.

How does the watchdog function interact with SPI communication and system safety?

The watchdog timer (t_WD = 272–400 μs) resets on every successful SPI frame transfer *and* on periodic internal refresh signals from the logic stage. If either stops - due to MCU freeze, SPI bus fault, or logic-stage power loss - all outputs disable within t_WD. This ensures fail-safe behavior even if the host controller becomes unresponsive, meeting SIL-2 functional safety requirements for industrial shutdown circuits.

Can ISO8200AQ drive loads with floating returns, or must the load be grounded?

The ISO8200AQ is strictly a high-side switch: each OUTx pin sources current from V_CC, and the load must be connected between OUTx and GND_CC. It cannot drive loads with floating or V_CC-referenced returns. Attempting to do so violates the device's grounding architecture and compromises isolation integrity, as GND_CC is the sole return path for all eight channels.

What is the role of the two exposed thermal pads (TAB(V_CC) and TAB(GND_CC)), and how should they be routed on PCB?

TAB(V_CC) is internally bonded to the V_CC power plane and must be soldered to a dedicated V_CC copper pour; TAB(GND_CC) connects to GND_CC and requires a separate, isolated ground pour. Both pads provide primary thermal conduction paths - routing them to large, multi-layer copper areas reduces R_th(j-case) to 1 °C/W. They must never be shorted or connected to GNDDD or system ground.