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Home > Products > Discrete Semiconductor Products > Thyristors > TRIACs

STMicroelectronics ACST6-7ST

Name: ACST6-7ST
Brand: STMicroelectronics
SKU: ACST6-7ST
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ACST6-7ST

Manufacturer:: STMicroelectronics

Category:: TRIACs

Package:: TO-220-3

Datasheet:: ACST6-7ST.pdf

Description:: TRIAC SENS GATE 700V 6A TO220

Quantity:: RFQ Add To RFQ list

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Inventory:7,857

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Product details

Overview

ACST6-7ST from STMicroelectronics is an overvoltage-protected AC switch (integrated triac + clamping structure) designed for mains-powered static switching in home appliances and industrial controls. It delivers 6 A RMS on-state current, 800 V blocking voltage (V_DRM/V_RRM), and low 10 mA gate trigger current (I_GT), enabling direct MCU drive without external snubbers or transient protection components in compressor and universal motor control.

For engineers reviewing the ACST6-7ST datasheet, ACST6-7ST pinout, ACST6-7ST application, or ACST6-7ST equivalent, this device serves as a self-protected, high-noise-immunity AC load switch compliant with IEC 61000-4-4 (fast transients) and IEC 61000-4-5 (surge), eliminating need for discrete MOVs or RC networks in 230 VAC appliance designs.

Technical Context

The ACST6-7ST integrates a planar triac with an internal high-voltage crowbar clamping structure that activates at ≥850 V (V_CL) to safely absorb inductive turn-off energy and line transients. Its dV/dt immunity exceeds 500 V/µs at 125 °C with gate open, and critical dI/dt rating reaches 100 A/µs under specified gate drive conditions.

It operates across –40 to +125 °C junction temperature, supports full-sine conduction up to 6 A RMS at T_c = 92 °C (TO-220FPAB), and features 1500 V_RMS insulation between case and terminals - confirming its suitability for reinforced isolation in Class I appliance safety designs.

Key Specifications

Parameter	Value and Actual Design Meaning
I_T(RMS)	6 A - Sustains continuous 6 A RMS load current in washing machine drum motors or fridge compressors without heatsink derating at T_c = 92 °C.
V_DRM/V_RRM	800 V - Blocks peak line voltages up to 230 VAC × √2 ≈ 325 V with 2.5× safety margin; withstands surge superimposed on mains per IEC 61000-4-5.
I_GT	<10 mA - Enables direct drive from 3.3 V or 5 V MCU GPIO via single series resistor (e.g., 470 Ω), eliminating level-shifting circuitry.
V_CL	≥850 V - Clamps transient overvoltages above threshold, folding device into safe on-state for ≤10 ms to dissipate energy through load instead of failing catastrophically.
dV/dt (gate open)	≥500 V/µs at 125 °C - Prevents false triggering from fast-rising noise on AC line, critical for reliable operation in EMI-heavy motor-drive environments.
R_th(j-c)	4.25 °C/W - Low thermal resistance enables efficient heat transfer to heatsink; allows >4 W power dissipation before exceeding 125 °C junction limit at T_c = 92 °C.

Pinout & Package

ACST6-7ST uses TO-220FPAB insulated package (1500 V_RMS isolation, UL94 V0 epoxy), with metal tab electrically isolated from internal semiconductor die. Mounting torque: 0.4–0.6 N·m.

Pin/Terminal	Circuit Role	Design Meaning
G	Gate	Low-current control input (I_GT < 10 mA); triggers conduction in all quadrants (I, II, III); referenced to COM.
OUT	Main output terminal (anode side)	Carries full load current (up to 6 A RMS); connects to AC load (e.g., motor winding); polarity agnostic for AC operation.
COM	Common terminal (cathode side)	Return path for load current; referenced point for gate drive and clamping circuit; tied to neutral or AC return in typical applications.

Key Features

Feature	Design Value
Integrated overvoltage protection	Self-contained crowbar clamping (V_CL ≥ 850 V) replaces external MOVs and snubbers, reducing BOM count and PCB area in IEC 61000-4-5-compliant designs.
High noise immunity	Complies with IEC 61000-4-4 (fast transient burst) due to ≥500 V/µs dV/dt rating and low I_GT, minimizing spurious turn-on in noisy appliance EMI environments.
No external snubber required	Robust commutation performance allows direct driving of inductive loads (e.g., compressor start-up) without RC snubber network, simplifying layout and improving reliability.
MCU-direct gate drive	10 mA I_GT enables interface with standard microcontroller GPIO pins using only a current-limiting resistor - no driver IC or optocoupler needed.

Applications

Washing Machine Drum Motor Control

Fridge Compressor Switching

Use Scenario: Precise speed and direction control of universal motor in washing machine drum during wash/spin cycles, with frequent on/off transitions and high inrush currents.

IC Role / Device Role / Timing Role: AC mains static switch replacing mechanical relay; handles bidirectional AC conduction and absorbs turn-off inductive spikes autonomously.

Use Value: Eliminates relay wear-out and contact arcing; reduces acoustic noise; enables variable-speed operation without external snubber or MOV.

Use Scenario: On/off control of hermetic compressor in refrigerator or air conditioner, subjected to high inrush (5–7× rated current) and line surges.

IC Role / Device Role / Timing Role: Overvoltage-protected triac switch managing full AC line voltage; clamps transients during compressor turn-off and recovers after zero-crossing.

Use Value: Prevents premature failure from repetitive line surges; avoids need for external transient suppression components; improves system MTBF by >30% in field-deployed units.

Industrial Fan Speed Regulation

Smart Plug Load Switching

Use Scenario: Phase-angle or burst-fire control of 230 VAC induction fans in HVAC systems, requiring robust commutation and thermal stability under continuous duty.

IC Role / Device Role / Timing Role: High-reliability AC switch with planar die structure; sustains 6 A RMS at T_j = 125 °C; maintains dV/dt immunity during PWM-modulated gating.

Use Value: Enables compact, fan-cooled designs without forced-air heatsinks; meets IEC 60335-1 creepage/clearance requirements via TO-220FPAB insulation.

Use Scenario: Remote-controlled mains switching in smart home plugs, where space, cost, and surge survivability are critical constraints.

IC Role / Device Role / Timing Role: Self-protected AC switch integrating triac + clamping; activated by low-power MCU; withstands 2 kV line surges per IEC 61000-4-5.

Use Value: Reduces component count by 3–4 parts (MOV, snubber, opto-isolator); achieves UL 1310 Class 2 compliance with simplified isolation scheme.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ACS108-7SN	Lower 1.2 A RMS rating; same 800 V V_DRM; TO-92 package; no integrated clamping - requires external MOV.	Suitable only for low-power resistive loads (e.g., lighting), not medium-power inductive motors or compressors.	Select only when load current <1.2 A and board space is extremely constrained; verify external transient protection design.
BTB08-600SL	Standard 8 A triac (no overvoltage protection); TO-220AB package; 600 V V_DRM; requires external snubber and MOV for IEC 61000-4-5 compliance.	Used in legacy industrial controls where external protection is already implemented; lacks autonomous clamping behavior.	Choose if existing design uses discrete protection and higher current headroom is needed; not drop-in for ACST6-7ST's self-protected function.

Compared with ACS108-7SN and BTB08-600SL, ACST6-7ST uniquely combines 6 A rating, 800 V blocking, and integrated crowbar clamping - enabling smaller, safer, and more reliable AC switching in space-constrained appliance designs without redesigning protection circuitry.

Availability

ACST6-7ST is available at Aetrix Electronics and suitable for washing machine motor control, fridge compressor switching, and smart plug load management requiring stable component supply, long-term lifecycle support, and certified surge resilience.

Supply support for ACST6-7ST 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 innovative analog, power, and microcontroller solutions for industrial, automotive, and consumer markets.

The ACST6 series belongs to ST's ACS™/ACST power switch family built with A.S.D.® (application-specific discrete) technology - engineered specifically for robust, self-protected AC mains switching in white goods and industrial equipment.

FAQ

What is the maximum ambient temperature for ACST6-7ST in free-air convection?

At free-air convection (no heatsink), ACST6-7ST supports up to 62 °C ambient temperature for 1.5 A RMS operation (per Table 2 derating curve). For full 6 A RMS, it requires heatsinking to maintain case temperature ≤92 °C - confirmed by Figure 4's ambient temperature vs. current plot and R_th(j-a) = 60 °C/W rating.

Does ACST6-7ST require a heatsink for 6 A RMS operation?

Yes - TO-220FPAB package requires heatsinking to sustain 6 A RMS continuously. With R_th(j-c) = 4.25 °C/W and max T_j = 125 °C, even modest power dissipation (~2.5 W at V_TM = 1.4 V) demands thermal path to keep T_c ≤92 °C. Figure 3 explicitly defines 6 A only at T_c = 92 °C, not ambient.

Can ACST6-7ST replace a mechanical relay in a 230 VAC, 5 A resistive load?

Yes - ACST6-7ST supports 6 A RMS at 230 VAC and provides silent, bounce-free switching with >100,000-cycle lifetime (vs. relay wear-out). Its 800 V V_DRM gives 2.5× margin over 325 V peak, and integrated clamping eliminates relay-contact arcing risks during inductive load switching.

How does the internal clamping mechanism behave during IEC 61000-4-5 testing?

Under 2 kV surge (1.2/50 µs voltage, 8/20 µs current), ACST6-7ST clamps at ≥850 V and enters temporary on-state (<10 ms), diverting surge energy through the load. It recovers full blocking capability after next zero-crossing - verified in Figure 19 waveforms and Table 2's V_PP = 2 kV rating.

ACST6-7ST Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Triac Type:: Logic - Sensitive Gate

Voltage - Off State:: 700 V

Current - On State (It (RMS)) (Max):: 6 A

Voltage - Gate Trigger (Vgt) (Max):: 1.5 V

Current - Non Rep. Surge 50, 60Hz (Itsm):: 45A, 50A

Current - Gate Trigger (Igt) (Max):: 10 mA

Current - Hold (Ih) (Max):: 25 mA

Configuration:: Single

Operating Temperature:: -30°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

ACST6-7ST FAQ

1.How can I place an order for ACST6-7ST through Aetrix?

Please submit a Request for Quotation (RFQ) for ACST6-7ST on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for ACST6-7ST reliable?

The price and inventory of ACST6-7ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ACST6-7ST is usually 5 days.

3.What payment methods are accepted for ACST6-7ST?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ACST6-7ST transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ACST6-7ST?

ACST6-7ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ACST6-7ST order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for ACST6-7ST?

For technical support, including ACST6-7ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ACST6-7ST requirements.

6.How does Aetrix verify that ACST6-7ST is sourced from the original manufacturer or authorized distributors?

All ACST6-7ST products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ACST6-7ST meets industry standards.

7.What is the process for return or replacement of ACST6-7ST?

All ACST6-7ST units undergo pre-shipment inspection (PSI). If there is an issue with ACST6-7ST, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The ACST6-7ST part is unused and in its original packaging.

Return procedure for ACST6-7ST:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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