STMicroelectronics ACST1035-7FP

Overview

ACST1035-7FP from STMicroelectronics is a 10 A, 700 V RMS overvoltage-protected AC switch (Triac) with integrated crowbar clamping, housed in an insulated TO-220FPAB package rated for 1500 V_RMS isolation. It delivers 2000 V/µs static dV/dt immunity at 125 °C and supports direct MCU gate drive with I_GT ≤ 35 mA - enabling robust control of universal motors and compressors in washing machines and refrigerators without external snubbers or transient protection.

For engineers reviewing the ACST1035-7FP datasheet, ACST1035-7FP pinout, ACST1035-7FP application, or ACST1035-7FP equivalent, this device is selected for high-noise industrial AC mains switching where IEC 61000-4-4/4-5 compliance, thermal reliability at T_c = 84 °C, and self-protecting turn-off behavior under inductive load transients are mandatory design requirements.

Technical Context

The ACST1035-7FP implements A.S.D.® (Application Specific Discrete) technology with planar Triac structure and monolithically integrated overvoltage crowbar circuitry. Its clamping voltage V_CL ≥ 850 V at 25 °C enables safe dissipation of IEC 61000-4-5-compliant 2 kV line surges by folding into conduction for <10 ms, then recovering blocking capability after zero-crossing.

It operates across quadrants I, II, and III with guaranteed static dV/dt ≥ 2000 V/µs at 125 °C and critical di/dt ≥ 4.4 A/ms without snubber - validated for compressor inrush and motor torque transients. Gate triggering is specified with V_OUT = 12 V, R_L = 33 Ω, and junction temperature up to 125 °C.

Key Specifications

Pinout & Package

ACST1035-7FP uses the TO-220FPAB insulated package: epoxy body with isolated metal tab rated for 1500 V_RMS isolation, UL94 V0 flammability rating, and recommended mounting torque of 0.4–0.6 N·m.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ACST1010-7FP, ACST1035-7FP trades lower gate sensitivity for higher noise immunity - critical in noisy appliance environments; versus BTB12-700CW, it eliminates BOM cost and board space for external protection while delivering certified surge resilience.

Availability

ACST1035-7FP is available at Aetrix Electronics and suitable for washing machine motor control, refrigerator compressor drive, and industrial AC solenoid actuation requiring stable component supply, long-term lifecycle support, and IEC-compliant transient ruggedness.

Supply support for ACST1035-7FP 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, digital, and mixed-signal ICs and discrete power devices for industrial, automotive, and consumer markets.

The ACST10 series belongs to ST's ACS™/ACST power switch family built with A.S.D.® technology - engineered specifically for robust, snubberless AC mains switching in home appliances and industrial controls where reliability under surge and thermal stress is non-negotiable.

FAQ

What is the maximum case temperature for continuous operation of ACST1035-7FP?

The ACST1035-7FP is rated for continuous operation with case temperature (T_c) up to 84 °C in the TO-220FPAB package, as defined in Table 2 of the datasheet. Exceeding this limit risks exceeding the 125 °C maximum junction temperature, potentially triggering thermal shutdown or degradation. Heatsink selection must ensure T_c ≤ 84 °C at 10 A RMS load current.

Does ACST1035-7FP require a heat sink in all applications?

Yes - the TO-220FPAB package has R_th(j-c) = 3.5 °C/W, meaning even at 5 A RMS load (P_cond ≈ 3.75 W), junction temperature rise exceeds safe limits without thermal management. A properly sized aluminum heatsink is mandatory for any sustained current >2 A, especially in enclosed or high-ambient environments.

Can ACST1035-7FP replace a standard Triac like BT139 without circuit changes?

No - while pin-compatible in TO-220FPAB footprint, ACST1035-7FP has higher gate trigger current (35 mA vs. ~50 mA for BT139), different dV/dt behavior, and active crowbar action that alters transient response. Direct replacement requires validation of gate drive strength, snubber removal, and surge test requalification per IEC 61000-4-5.

How does the overvoltage crowbar function during a 2 kV surge event?

When line voltage exceeds V_CL (≥850 V), the internal crowbar activates, forcing the device into low-impedance conduction for <10 ms. Current flows through the load (not the device alone), limiting peak power dissipation. After current crosses zero, the device regains full blocking capability - verified for ≥10 such events per polarity per datasheet Figure 18.