STMicroelectronics ACST2-8SB-TR

Overview

ACST2-8SB-TR from STMicroelectronics is an overvoltage-protected AC switch (sensitive triac) with integrated crowbar clamping, rated for 2 A RMS on-state current and 800 V blocking voltage in DPAK package. It features low gate trigger current (IGT ≤ 10 mA), high static dV/dt immunity (>500 V/µs at 125 °C), and self-protection against IEC 61000-4-5 line transients up to 2 kV peak. It directly interfaces with microcontrollers to drive inductive loads like solenoids and fans in appliance control.

For engineers reviewing the ACST2-8SB-TR datasheet, ACST2-8SB-TR pinout, ACST2-8SB-TR application, or ACST2-8SB-TR equivalent, this device is selected for robust AC static switching where external snubbers are undesirable, IEC-compliant surge resilience is mandatory, and logic-level gate drive with high noise immunity is required in space-constrained designs.

Technical Context

The ACST2-8SB-TR integrates a planar triac structure with an internal high-voltage clamping device that activates during overvoltage events (VCL ≥ 850 V), folding the device into a safe on-state for <10 ms to dissipate energy through the load. Its gate sensitivity (IGT ≤ 10 mA) enables direct MCU GPIO drive via a single series resistor without buffer stages.

It achieves 500 V/µs static dV/dt at 125 °C - 5–10× higher than standard triacs of comparable IGT - due to optimized semiconductor layout and A.S.D.® (Application Specific Discrete) process technology. Thermal resistance Rth(j-c) is 4.5 °C/W (DPAK), supporting 2 A RMS operation at TC ≤ 110 °C without forced cooling.

Key Specifications

Pinout & Package

DPAK (TO-252) surface-mount package with insulated tab; thermally enhanced for PCB conduction cooling. Tab is electrically connected to COM terminal.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar AC switch applications.

Compared with ACS108-6SN and BTB08-600SL, ACST2-8SB-TR uniquely combines logic-level gate drive, integrated crowbar protection, and DPAK thermal efficiency - making it optimal for compact, IEC-certified, microcontroller-driven AC switching below 2 A.

Availability

ACST2-8SB-TR is available at Aetrix Electronics and suitable for appliance motor control, industrial solenoid actuation, and smart lighting interface applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant DPAK packaging.

Supply support for ACST2-8SB-TR 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, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The ACST2 series belongs to ST's ACS™/ACST power switch family built with A.S.D.® (Application Specific Discrete) technology - engineered specifically for reliable, snubberless AC load switching in cost-sensitive, space-constrained white goods and industrial controls.

FAQ

Is ACST2-8SB-TR compatible with zero-crossing detection circuits?

Yes. Its low IGT (≤10 mA) and stable holding current (IH ≤ 10 mA) allow clean synchronization with zero-crossing optocouplers or MCU-based timing. The device maintains blocking integrity during voltage transitions and exhibits minimal leakage (<10 µA), ensuring accurate zero-detection window fidelity without false triggering.

Does ACST2-8SB-TR require a heatsink for 2 A RMS operation?

No external heatsink is required. With Rth(j-c) = 4.5 °C/W and recommended 0.5 cm² copper area under the tab, the DPAK package dissipates heat effectively. At TC = 110 °C, it sustains 2 A RMS continuously - verified per Figure 3 in the datasheet - making it suitable for double-sided PCB layouts with thermal vias.

Can ACST2-8SB-TR replace a mechanical relay in a 230 V AC, 1.5 A fan application?

Yes - and with improved reliability. It switches faster, eliminates contact arcing and wear, and withstands inductive turn-off energy without snubbers. Its 800 V VDRM provides 1.7× margin over 230 V RMS peaks, and its crowbar protection handles line surges that would degrade relay contacts over time.

What is the maximum allowable gate resistor value when driving from a 3.3 V MCU?

For guaranteed turn-on across temperature and process variation, the gate resistor must limit current to ≥10 mA at worst-case VGS. With 3.3 V supply and VGT ≤ 1.1 V, Rg ≤ (3.3 − 1.1) V / 10 mA = 220 Ω. A 220 Ω resistor ensures robust triggering while limiting peak gate power to <10 W (per PGM spec) during 20 µs pulses.