STMicroelectronics ACST410-8BTR

Overview

ACST410-8BTR from STMicroelectronics is a 4 A, 800 V insulated AC switch with integrated overvoltage clamping, designed as a self-protected triac replacement for mains-connected static switching in home appliances and industrial controls. It features low gate trigger current (IGT < 10 mA), high static dV/dt immunity (>1000 V/μs at 125 °C), and TO-220FPAB package with 2000 VRMS insulation - enabling direct MCU drive and elimination of external snubbers in compressor and drum motor control.

For engineers reviewing the ACST410-8BTR datasheet, ACST410-8BTR pinout, ACST410-8BTR application, or ACST410-8BTR equivalent, this device is selected for IEC 61000-4-4/4-5 compliant AC load switching where high noise immunity, zero-crossing–compatible turn-off, and intrinsic surge ruggedness are required without external protection components.

Technical Context

The ACST410-8BTR implements a planar triac structure with monolithically integrated voltage-clamping crowbar circuitry, enabling automatic transition to on-state during >850 V transients (VCL min) and safe dissipation of IEC 61000-4-5 2 kV surges. Its gate-trigger threshold remains stable across -40 to +125 °C junction temperature, with IGT ≤ 10 mA and VGT ≤ 1.0 V under standard test conditions.

Thermal performance is defined by Rth(j-c) = 4.6 °C/W (TO-220FPAB), supporting 4 A RMS conduction at Tc = 102 °C. The device sustains dI/dt ≥ 100 A/μs without commutation failure and maintains off-state leakage <0.5 mA at 125 °C and 800 V blocking voltage.

Key Specifications

Pinout & Package

ACST410-8BTR uses the TO-220FPAB insulated package: epoxy body rated UL94 V0, 3-pin configuration with electrically isolated tab (COM), and mechanical dimensions per DS2762 Rev 12 Figure 19 (A=4.4–4.6 mm, L3=28.6–30.6 mm, Dia=3.0–3.2 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ACST410-8FP, ACST410-8BTR offers optimized logistics for SMT production; compared with ACST435-8BTR, it provides lower gate drive burden at the cost of slightly reduced dV/dt margin - making it ideal for clean MCU-driven systems prioritizing efficiency and component count reduction.

Availability

ACST410-8BTR is available at Aetrix Electronics and suitable for washing machine motor control, refrigerator compressor switching, and smart plug load management requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for ACST410-8BTR 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 analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The ACST4 series belongs to ST's ACS/ACST power switch family, engineered specifically for robust, snubberless AC mains control in white goods and industrial equipment where reliability under surge and thermal stress is non-negotiable.

FAQ

What is the maximum allowable gate resistor value for reliable triggering with a 3.3 V MCU?

A 330 Ω resistor limits gate current to ~10 mA at 3.3 V, satisfying the IGT ≤ 10 mA requirement while maintaining VGT ≤ 1.0 V. Lower resistance (e.g., 220 Ω) improves noise margin but increases MCU pin loading; values above 470 Ω risk marginal triggering at high temperature due to IGT drift.

Can ACST410-8BTR replace a standard triac like BT139-800 in existing designs?

Yes - it is pin-compatible with BT139-800 in TO-220FPAB footprint and matches its 800 V VDRM and 4 A IT(RMS). However, ACST410-8BTR adds intrinsic overvoltage clamping and higher dV/dt immunity, allowing removal of external snubbers and MOVs without redesigning PCB layout or gate drive.

Does the 2000 VRMS insulation rating apply to creepage/clearance distances on the PCB?

No - the 2000 VRMS rating applies only to the internal package insulation (tab-to-pin). PCB creepage and clearance must still comply with IEC 60664-1: minimum 4.0 mm creepage and 2.5 mm clearance for reinforced insulation at 230 VAC mains, independent of the device's internal rating.

How does the device recover after an overvoltage event that triggers crowbar action?

After clamping or crowbar turn-on, ACST410-8BTR automatically recovers blocking capability at the next AC zero-crossing. No reset or external intervention is needed; the device resumes normal operation within ≤10 ms and withstands ≥10 such events per polarity per IEC 61000-4-5 compliance testing.