STMicroelectronics ACST4-7CH

Overview

ACST4-7CH from STMicroelectronics is a 700 V, 4 A AC power switch in DPAK package, featuring integrated Triac structure with avalanche clamping (V_CL = 1100 V), gate-trigger current < 10 mA, and static dV/dt >500 V/µs. It directly interfaces with microcontrollers to drive inductive loads such as dishwasher spray pumps and air-conditioner fans without external snubbers or overvoltage protection.

For engineers reviewing the ACST4-7CH datasheet, ACST4-7CH pinout, ACST4-7CH application, or ACST4-7CH equivalent, this device offers verified IEC 61000-4-5 transient ruggedness (2 kV line surge), high commutation robustness (dI/dt = 50 A/µs), and thermal performance validated at T_c = 110 °C for continuous 4 A RMS conduction.

Technical Context

The ACST4-7CH implements ASD™ technology - a planar Triac with monolithically integrated voltage clamping - enabling safe turn-off of highly inductive loads without external snubbers. Its gate-triggering threshold (I_GT ≤ 10 mA, V_GT ≤ 1 V) and low holding current (I_H ≤ 20 mA) support direct logic-level drive from 3.3 V or 5 V MCUs.

It sustains non-repetitive 2 kV line transients per IEC 61000-4-5 (R = 150 Ω, L = 10 µH), with clamping action limiting peak voltage to 1100 V while maintaining off-state leakage < 10 µA at 25 °C and < 500 µA at 125 °C.

Key Specifications

Pinout & Package

DPAK (TO-252) package with exposed thermal pad; 3-pin surface-mount configuration optimized for high-current, low-inductance PCB routing and thermal dissipation via copper pour under tab.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ACST4-7CB and ACS108-7SN, the ACST4-7CH provides optimal balance of low gate drive demand, full 4 A RMS capability, and certified 2 kV surge resilience - making it the preferred choice for primary load switching in white goods and industrial controls where reliability and component count reduction are critical.

Availability

ACST4-7CH is available at Aetrix Electronics and suitable for dishwasher spray pump control, air-conditioner fan drive, washing machine drain pump actuation, and smart plug load switching requiring stable component supply across production lifecycles.

Supply support for ACST4-7CH 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, delivering silicon solutions for automotive, industrial, and consumer markets with emphasis on reliability, integration, and energy efficiency.

The ACST4 Series belongs to ST's ASD™ AC power switch product line, engineered specifically for solid-state replacement of electromechanical relays in home appliance motor and solenoid control - prioritizing surge immunity, gate simplicity, and thermal robustness in space-constrained designs.

FAQ

What is the maximum allowable case temperature for continuous 4 A RMS operation?

The ACST4-7CH supports 4 A RMS conduction at T_c = 110 °C in DPAK package, as specified in the Absolute Ratings table. Exceeding this temperature requires derating per Figure 2-1; at T_c = 100 °C, RMS current remains at 4 A, but drops to ~3.2 A at T_c = 125 °C. Thermal design must ensure copper area under the tab meets minimum 0.5 cm² on FR4 for stated R_th(j-a) = 70 °C/W.

Does ACST4-7CH require a heatsink for 4 A RMS operation in free-air conditions?

No dedicated heatsink is required if PCB layout provides ≥0.5 cm² copper area under the DPAK thermal pad on FR4 board with 35 µm copper thickness. Under those conditions, R_th(j-a) = 70 °C/W allows junction temperature to stay within −30 to +125 °C range at T_a = 70 °C ambient. Forced airflow or larger copper pours further improve margin but are not mandatory for nominal operation.

Can ACST4-7CH be used in zero-crossing switching applications?

Yes - though not internally zero-crossing triggered, its high dV/dt immunity (>500 V/µs) and low I_GT enable reliable synchronization with external zero-crossing detection circuits. Gate timing can be precisely controlled by MCU to initiate conduction near voltage zero, minimizing EMI and inrush current. No internal timing circuitry is present; all phase control is externally managed.

Is ACST4-7CH compliant with RoHS and REACH regulations?

Yes - ACST4-7CH is manufactured in STMicroelectronics' RoHS-compliant and REACH-conformant facilities. The DPAK package uses lead-free matte tin plating, and the epoxy molding compound meets UL94 V-0 flammability rating. Full compliance documentation, including substance declarations and test reports, is available through ST's official product portal under document number CD00159749.