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STMicroelectronics ACST2-8SB
- Part No.:
- ACST2-8SB
- Manufacturer:
- STMicroelectronics
- Category:
- TRIACs
- Package:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Datasheet:
-
ACST2-8SB.pdf
- Description:
- TRIAC SENS GATE 800V 2A DPAK
- Quantity:
- Payment:
- Shipping:
Inventory:9,178
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Product details
Overview
ACST2-8SB from STMicroelectronics is a 2 A, 800 V RMS overvoltage-protected AC switch (Triac with integrated crowbar clamping), designed for direct microcontroller-driven AC on/off control of inductive loads such as solenoids, fans, and pumps in home appliances and industrial systems. It features IGT ≤ 10 mA gate sensitivity, dV/dt ≥ 500 V/µs at 125 °C, and VCL ≥ 850 V clamping voltage.
For engineers reviewing the ACST2-8SB datasheet, ACST2-8SB pinout, ACST2-8SB application, or ACST2-8SB equivalent, this device is selected for robust IEC 61000-4-4/4-5 compliant AC switching where self-protected transient handling, low gate drive current, and snubberless inductive load control are required.
Technical Context
The ACST2-8SB integrates a planar Triac structure with an on-die overvoltage crowbar circuit that triggers into conduction during line transients exceeding VCL (≥850 V), safely diverting surge energy through the load. Its high static dV/dt (≥500 V/µs) and fast transient immunity stem from optimized gate layout and junction design, not external RC networks.
It operates in quadrants I, II, and III with symmetrical triggering behavior, supports full-cycle sine-wave conduction up to 2 A RMS, and recovers blocking capability after crowbar events at the next zero-crossing - enabling repeatable surge withstand per IEC 61000-4-5 (≥10 cycles).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IT(RMS) | 2 A - Sustains continuous resistive/inductive load current without heatsink derating up to Tc = 110 °C (DPAK). |
| VDRM / VRRM | 800 V - Blocks 800 V peak AC line voltage (115/230 V mains + margin), enabling global appliance use. |
| IGT (max) | 10 mA - Driven directly by MCU GPIO via single series resistor; no buffer stage needed. |
| dV/dt (min) | 500 V/µs @ 125 °C - Immune to fast transients (IEC 61000-4-4); eliminates false triggering in noisy industrial environments. |
| VCL (min) | 850 V @ 25 °C - Clamps inductive turn-off spikes and line surges; initiates crowbar mode before destructive breakdown. |
| VTM (max) | 2 V @ 2.8 A - Low on-state loss (≤5.6 W at 2 A) enables compact thermal design in sealed enclosures. |
| Rth(j-c) | 4.5 °C/W (DPAK) - Enables >1.5 W power dissipation with minimal case-to-heatsink thermal resistance. |
Pinout & Package
ACST2-8SB is supplied in the DPAK (TO-252) surface-mount package, featuring isolated tab for PCB thermal relief and UL94 V0 epoxy molding. The package has three terminals: Gate (G), Main Terminal 1 (COM), and Main Terminal 2 (OUT).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| G | Gate input | Low-current trigger input (IGT ≤ 10 mA); referenced to COM; controls bidirectional conduction onset. |
| COM | Main terminal 1 (common) | Reference node for gate drive and load return path; connected to neutral or low-side AC line in typical configurations. |
| OUT | Main terminal 2 (output) | Switched AC output terminal; connects to load; voltage polarity reverses each half-cycle relative to COM. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated overvoltage crowbar protection | Self-triggering clamping at VCL ≥ 850 V eliminates need for external MOVs or snubbers in IEC 61000-4-5 compliant designs. |
| Snubberless inductive load switching | Drives solenoids, pumps, and fans up to 2 A RMS without external RC suppression due to controlled commutation and high dI/dt rating (50 A/µs). |
| Direct microcontroller interface | IGT ≤ 10 mA allows GPIO-level drive with single 330 Ω resistor from 3.3 V or 5 V logic, reducing BOM count and board space. |
| High noise immunity | Static dV/dt ≥ 500 V/µs at 125 °C ensures reliable operation in EMI-heavy environments like motor drives and HVAC control panels. |
| Insulation-rated isolation | DPAK variant provides reinforced insulation between die and PCB copper; supports functional safety requirements in Class I appliances. |
Applications
| Washing Machine Door Lock Control | Industrial Fan Speed Staging |
|---|---|
|
Use Scenario: Controlling 24 V AC solenoid lock in washing machine door latch assembly, activated only during spin cycle. IC Role / Device Role / Timing Role: AC on/off switch triggered by MCU PWM signal synchronized to zero-crossing detection; handles inductive kickback without snubber. Use Value: Eliminates external TVS and RC snubber, reduces component count by 3 parts, and meets IEC 61000-4-5 Level 3 surge immunity (2 kV line-earth). |
Use Scenario: Staged activation of 120 V AC shaded-pole fans in HVAC duct system based on temperature thresholds. IC Role / Device Role / Timing Role: Zero-crossing–triggered AC switch enabling soft-start and phase-angle–free on/off control for EMI reduction. Use Value: Withstands repeated inductive turn-off transients from fan windings; maintains >10⁵ switching cycles without degradation due to planar Triac structure. |
| Smart Plug Load Switching | Commercial Coffee Maker Pump Control |
|
Use Scenario: Remote-controlled switching of 230 V AC resistive heating element and small AC motor in Wi-Fi–enabled smart plug. IC Role / Device Role / Timing Role: Primary AC power switch interfaced directly to ESP32 GPIO; clamps lightning-induced surges on mains input. Use Value: VCL ≥ 850 V and 2 kV surge withstand (per IEC 61000-4-5) enable CE/UKCA compliance without external protection components. |
Use Scenario: Driving 115 V AC peristaltic pump in commercial espresso machine, cycling on/off during brew and steam phases. IC Role / Device Role / Timing Role: Snubberless AC switch managing highly inductive pump load with rapid duty cycling (≤1 s ON/OFF). Use Value: High dI/dt (50 A/µs) and low IL (≤25 mA) ensure reliable turn-on even under cold-start inrush; reduces thermal stress vs. standard Triac. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar AC switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ACS108-8SN | Lower IT(RMS) = 1 A; same VDRM = 800 V; IGT = 10 mA; DPAK package; no crowbar - relies on external MOV. | Suitable only for sub-1 A resistive loads; requires external overvoltage protection for IEC 61000-4-5 compliance. | Select when cost is critical and surge levels are limited to <1 kV; not recommended for inductive loads >0.5 A. |
| BTB12-800CW | Standard Triac; IT(RMS) = 12 A; VDRM = 800 V; IGT = 50 mA; TO-220 package; dV/dt = 50 V/µs @ 125 °C. | Requires gate buffer driver and external snubber; cannot self-protect against line surges; higher gate power demand. | Select only for high-current (>5 A), non-safety-critical applications where crowbar function is unnecessary and board space permits discrete protection. |
Compared with ACS108-8SN and BTB12-800CW, ACST2-8SB uniquely combines 2 A rating, 10 mA gate sensitivity, 500 V/µs noise immunity, and integrated crowbar - enabling compact, certified, snubberless AC switching unattainable with either alternative.
Availability
ACST2-8SB is available at Aetrix Electronics and suitable for washing machine control modules, smart plug power stages, HVAC fan staging circuits, and commercial coffee maker pump drivers requiring stable component supply and long-term industrial lifecycle support.
Supply support for ACST2-8SB 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, specializing in power management, analog, microcontrollers, and automotive ICs with vertical manufacturing and broad industrial qualification.
The ACST™/ACST2 family was developed as part of ST's Application-Specific Discrete (A.S.D.®) initiative to replace electromechanical relays and standard Triacs in safety-critical AC load control, targeting IEC-compliant white goods and industrial automation.
FAQ
Is ACST2-8SB compatible with zero-crossing detection circuits?
Yes. ACST2-8SB supports zero-crossing–triggered switching: its gate can be driven synchronously with AC line zero crossings using an optocoupler or dedicated zero-crossing detector. This minimizes EMI and inrush current, and extends load lifetime - especially critical for incandescent lamps and transformer-coupled loads.
Does ACST2-8SB require a heatsink in 2 A continuous operation?
No heatsink is required for 2 A RMS operation at ambient temperatures ≤50 °C with ≥0.5 cm² copper area under the DPAK tab (FR4 PCB, 35 µm Cu). Thermal resistance Rth(j-a) drops to ~70 °C/W under those conditions, limiting junction temperature to <110 °C - within the 125 °C max rating.
Can ACST2-8SB replace mechanical relays in appliance applications?
Yes - it replaces SPST AC relays driving loads ≤2 A resistive or inductive. Its solid-state construction offers >10⁶ switching cycles, silent operation, no contact bounce, and immunity to vibration. Unlike relays, it requires no coil drive circuitry and delivers faster response (<100 ns turn-on delay).
What is the maximum surge voltage ACST2-8SB can withstand without crowbar activation?
ACST2-8SB clamps reliably at VCL ≥850 V (measured at 25 °C). Per IEC 61000-4-5 testing, it withstands 2 kV combined wave surges (1.2/50 µs voltage, 8/20 µs current) superimposed on 230 V AC mains - activating crowbar only during the surge event and recovering full blocking capability at the next zero-crossing.
ACST2-8SB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Packaging:
- Tube
- Product Status:
- Obsolete
- Triac Type:
- Logic - Sensitive Gate
- Voltage - Off State:
- 800 V
- Current - On State (It (RMS)) (Max):
- 2 A
- Voltage - Gate Trigger (Vgt) (Max):
- 1.1 V
- Current - Non Rep. Surge 50, 60Hz (Itsm):
- 8A, 8.4A
- Current - Gate Trigger (Igt) (Max):
- 10 mA
- Current - Hold (Ih) (Max):
- 10 mA
- Configuration:
- Single
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DPAK
ACST2-8SB FAQ
1.How can I place an order for ACST2-8SB through Aetrix?
Please submit a Request for Quotation (RFQ) for ACST2-8SB 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 ACST2-8SB reliable?
The price and inventory of ACST2-8SB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ACST2-8SB is usually 5 days.
3.What payment methods are accepted for ACST2-8SB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ACST2-8SB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ACST2-8SB?
ACST2-8SB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ACST2-8SB 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 ACST2-8SB?
For technical support, including ACST2-8SB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ACST2-8SB requirements.
6.How does Aetrix verify that ACST2-8SB is sourced from the original manufacturer or authorized distributors?
All ACST2-8SB 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 ACST2-8SB meets industry standards.
7.What is the process for return or replacement of ACST2-8SB?
All ACST2-8SB units undergo pre-shipment inspection (PSI). If there is an issue with ACST2-8SB, 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 ACST2-8SB part is unused and in its original packaging.
Return procedure for ACST2-8SB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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