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Home > Products > Discrete Semiconductor Products > Thyristors > TRIACs

STMicroelectronics ACST12-7SG

Name: ACST12-7SG
Brand: STMicroelectronics
SKU: ACST12-7SG
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ACST12-7SG

Manufacturer:: STMicroelectronics

Category:: TRIACs

Package:: TO-263-3, D2PAK (2 Leads + Tab), TO-263AB

Datasheet:: ACST12-7SG.pdf

Description:: TRIAC SENS GATE 700V 12A D2PAK

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Product details

Overview

ACST12-7SG from STMicroelectronics is a transient-protected AC power switch integrating a 12 A TRIAC with overvoltage crowbar clamping (V_CL = 850 V) and low gate trigger current (I_GT < 10 mA). It operates up to 700 V repetitive peak off-state voltage, delivers 1.5 V on-state voltage at 17 A, and is packaged in D²PAK for high thermal performance in appliance motor control.

For engineers reviewing the ACST12-7SG datasheet, ACST12-7SG pinout, ACST12-7SG application, or ACST12-7SG equivalent, this device serves as a self-protected, snubberless AC mains switch for inductive loads-requiring no external transient protection while meeting IEC 61000-4-4/4-5 immunity standards.

Technical Context

The ACST12-7SG implements an integrated crowbar protection architecture that triggers into conduction during line transients exceeding V_CL, safely diverting surge energy through the load without external components. Its planar TRIAC structure ensures stable off-state blocking (I_DRM ≤ 20 µA at 25 °C) and high static dV/dt immunity (≥200 V/µs at 125 °C).

It supports direct MCU drive via a single series gate resistor due to its low I_GT (≤10 mA), and sustains repetitive 12 A RMS current with R_th(j-c) = 2.5 °C/W (D²PAK), enabling robust thermal management in compressor and drum motor applications without heatsink dependency under defined PCB copper area.

Key Specifications

Parameter	Value and Actual Design Meaning
I_T(RMS)	12 A - Sustains continuous AC load current up to 12 A without derating when mounted on 1 cm² Cu PCB
V_DRM/V_RRM	700 V - Blocks 700 V peak AC line voltage, suitable for 230 V mains with safety margin
I_GT	<10 mA - Enables direct drive from 3.3 V/5 V MCU GPIO with simple resistor limiting
V_CL	850 V - Clamps transients per IEC 61000-4-5; eliminates need for MOV or TVS
dV/dt (static)	≥200 V/µs @ 125 °C - Prevents false turn-on from electrical noise in industrial environments
R_th(j-a)	45 °C/W - Achieves 125 °C max junction temp with 1 cm² Cu pad, enabling compact layout
V_TM	1.5 V @ 17 A - Low conduction loss reduces heat generation vs. standard TRIACs

Pinout & Package

ACST12-7SG is housed in a surface-mount D²PAK (TO-263) package with three terminals: Gate (G), Main Terminal 1 (COM), and Main Terminal 2 (OUT). The exposed tab is electrically connected to COM and serves as primary thermal path.

Pin/Terminal	Circuit Role	Design Meaning
G	Gate control input	Low-current trigger node (I_GT < 10 mA); referenced to COM; requires no negative voltage
COM	Main terminal 1 / return path	Common connection point for load return and heatsink; electrically tied to exposed metal tab
OUT	Main terminal 2 / load output	Switched AC output to load; bidirectional conduction path with COM; handles full 12 A RMS

Key Features

Feature	Design Value
Integrated overvoltage crowbar	Clamps transients to 850 V and switches on to shunt surge energy-no external MOV or snubber required
Snubberless inductive switching	Drives universal motors and compressors up to 12 A without RC snubber, reducing BOM count and board space
High noise immunity	Static dV/dt ≥ 200 V/µs at 125 °C ensures reliable operation in EMI-heavy appliance environments
MCU-compatible gate drive	I_GT < 10 mA allows direct interface with standard microcontroller GPIO pins using only a series resistor
Planar technology reliability	Guarantees low leakage (I_DRM ≤ 20 µA at 25 °C) and stable blocking behavior over temperature and lifetime

Applications

Washing Machine Drum Motor Control

Refrigerator Compressor Drive

Use Scenario: Precise speed and direction control of universal AC motors in washing machine cycles (wash, spin, rinse).

IC Role / Device Role / Timing Role: AC mains switch replacing mechanical relays; provides zero-crossing–independent phase-angle control and transient-safe commutation.

Use Value: Eliminates relay wear-out and contact arcing; withstands repeated inrush currents (e.g., 120 A surge for 20 ms) without degradation.

Use Scenario: Start-stop and run control of hermetic compressors in refrigeration systems with PTC starter circuits.

IC Role / Device Role / Timing Role: High-reliability AC power switch handling high inrush (≥6× rated current) and sustained 12 A RMS load current.

Use Value: Withstands compressor startup surges and line transients per IEC 61000-4-5 without external protection, reducing failure rate in field use.

Air Conditioner Fan & Compressor Control

Industrial AC Load Sequencing Panel

Use Scenario: Dual-channel switching for indoor fan and outdoor compressor in split-system air conditioners.

IC Role / Device Role / Timing Role: Isolated AC power switch enabling independent control of two medium-power loads from a single MCU.

Use Value: Single-device solution replaces dual-relay assemblies; meets EMC Class B requirements without added filtering.

Use Scenario: Programmable sequencing of multiple AC-powered actuators (valves, heaters, pumps) in factory automation panels.

IC Role / Device Role / Timing Role: Solid-state replacement for electromechanical contactors in DIN-rail mounted control cabinets.

Use Value: Enables silent, bounce-free switching with 100 k-cycle lifetime vs. 100 k mechanical operations; supports remote diagnostics via gate monitoring.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ACST12-7CG	Same D²PAK package and 12 A rating, but high-immunity version (I_GT < 35 mA, dV/dt ≥ 2000 V/µs)	Better suited for noisy industrial settings where gate drive margin is limited and EMI is extreme	Select ACST12-7CG when system-level noise exceeds 200 V/µs or gate drive current >10 mA is available
ACS108-7SN	Lower current rating (8 A), same 700 V V_DRM, identical D²PAK footprint, and I_GT < 10 mA	Targeted for lighter loads (e.g., small fans, solenoids); not rated for compressor inrush	Choose ACS108-7SN only for sub-8 A RMS applications where thermal headroom and cost are prioritized

Compared with ACST12-7CG, the -7SG offers lower gate drive burden but reduced dV/dt immunity; versus ACS108-7SN, it delivers 50% higher current capacity and superior surge endurance-critical for compressor and drum motor duty cycles.

Availability

ACST12-7SG is available at Aetrix Electronics and suitable for washing machine motor control, refrigerator compressor drive, and industrial AC load sequencing requiring stable component supply across multi-year production programs.

Supply support for ACST12-7SG 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 for automotive, industrial, and consumer markets.

The ACST12 series belongs to ST's ASD (Application-Specific Discrete) portfolio, engineered specifically for robust, snubberless AC mains switching in home appliances and industrial controls-prioritizing transient resilience, thermal efficiency, and MCU compatibility.

FAQ

What is the maximum ambient temperature for ACST12-7SG at 12 A RMS with 1 cm² copper?

At 12 A RMS load current and with 1 cm² of copper on the PCB, the ACST12-7SG achieves a junction-to-ambient thermal resistance of 45 °C/W. With a maximum junction temperature of 125 °C and typical power dissipation of ~1.8 W (V_TM × I_T), the maximum allowable ambient temperature is approximately 71 °C-verified per Figure 4 in the official datasheet.

Does ACST12-7SG require a heat sink in TO-220AB form factor?

No-the ACST12-7SG is only offered in D²PAK (not TO-220AB); the TO-220AB variant is ACST12-7ST/7CT. In D²PAK, thermal performance relies on PCB copper area: 1 cm² Cu pad yields R_th(j-a) = 45 °C/W, sufficient for 12 A RMS at ≤71 °C ambient without an external heatsink.

Can ACST12-7SG replace a standard TRIAC like BT139-600 in existing designs?

Yes-with circuit modifications: gate resistor value must be recalculated for I_GT < 10 mA (vs. ~35 mA for BT139), and external MOV/snubber can be removed due to integrated crowbar. Pinout differs (G-COM-OUT vs. MT1-MT2-G), so PCB layout revision is required for D²PAK footprint and thermal pad routing.

How many IEC 61000-4-5 surge events can ACST12-7SG withstand?

The ACST12-7SG is rated to withstand ≥10 non-repetitive 2 kV surges (per IEC 61000-4-5 test waveform) on each AC line polarity, provided the load limits current and junction temperature remains within 125 °C. This is confirmed in Section 2.2 and Figure 19 of the datasheet, with recovery of blocking capability post-surge.

ACST12-7SG Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-263-3, D2PAK (2 Leads + Tab), TO-263AB

Packaging:: Tube

Product Status:: Obsolete

Triac Type:: Logic - Sensitive Gate

Voltage - Off State:: 700 V

Current - On State (It (RMS)) (Max):: 12 A

Voltage - Gate Trigger (Vgt) (Max):: 1 V

Current - Non Rep. Surge 50, 60Hz (Itsm):: 120A, 126A

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

Current - Hold (Ih) (Max):: 30 mA

Configuration:: Single

Operating Temperature:: -40°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: D2PAK

ACST12-7SG FAQ

1.How can I place an order for ACST12-7SG through Aetrix?

Please submit a Request for Quotation (RFQ) for ACST12-7SG 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 ACST12-7SG reliable?

The price and inventory of ACST12-7SG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ACST12-7SG is usually 5 days.

3.What payment methods are accepted for ACST12-7SG?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ACST12-7SG transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ACST12-7SG?

ACST12-7SG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ACST12-7SG 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 ACST12-7SG?

For technical support, including ACST12-7SG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ACST12-7SG requirements.

6.How does Aetrix verify that ACST12-7SG is sourced from the original manufacturer or authorized distributors?

All ACST12-7SG 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 ACST12-7SG meets industry standards.

7.What is the process for return or replacement of ACST12-7SG?

All ACST12-7SG units undergo pre-shipment inspection (PSI). If there is an issue with ACST12-7SG, 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 ACST12-7SG part is unused and in its original packaging.

Return procedure for ACST12-7SG:

1.Submit a request within 90 days.

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

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