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STMicroelectronics ACST12-7CT
- Part No.:
- ACST12-7CT
- Manufacturer:
- STMicroelectronics
- Category:
- TRIACs
- Package:
- TO-220-3
- Datasheet:
-
ACST12-7CT.pdf
- Description:
- TRIAC 700V 12A TO220
- Quantity:
- Payment:
- Shipping:
Inventory:859
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Product details
Overview
ACST12-7CT from STMicroelectronics is a transient-protected AC power switch integrating a 12 A TRIAC with overvoltage crowbar clamping (VCL = 850 V) and high static dV/dt immunity (≥2000 V/µs). It operates at 700 V repetitive peak off-state voltage, requires ≤35 mA gate trigger current (IGT), and is housed in a TO-220AB package for direct mounting on heatsinks. It enables IEC 61000-4-5-compliant AC mains switching in washing machine drum motors.
For engineers reviewing the ACST12-7CT datasheet, ACST12-7CT pinout, ACST12-7CT application, or ACST12-7CT equivalent, this device is selected for robust medium-power AC load control where self-protecting clamping, snubberless inductive turn-off, and MCU-direct gate drive (via simple resistor) are critical design requirements.
Technical Context
The ACST12-7CT implements an integrated crowbar protection architecture that switches to conduction during line transients ≥2 kV (per IEC 61000-4-5), clamping voltage to 850 V while dissipating energy through the load. Its planar TRIAC structure ensures stable off-state blocking up to 700 V with IDRM ≤1.5 mA at 125 °C.
It delivers snubberless commutation for inductive loads up to 12 A RMS, supported by critical dI/dt rating of 100 A/µs and (dI/dt)c ≥14 A/ms without external snubber. Gate triggering is specified across quadrants I/II/III with IGT ≤35 mA and VGT ≤1.0 V at 25 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IT(RMS) | 12 A - Sustains continuous sinusoidal load current without thermal derating at Tc = 104 °C |
| VDRM/VRRM | 700 V - Blocks AC line peaks up to 495 V RMS (e.g., 230 VAC + margin) with <1.5 mA leakage at 125 °C |
| IGT (max) | 35 mA - Compatible with standard MCU GPIOs using ≤330 Ω series gate resistor |
| dV/dt (min) | 2000 V/µs - Immune to fast EFT bursts per IEC 61000-4-4 without false triggering |
| VCL | 850 V - Clamps transient overvoltages to safe level, enabling compliance with IEC 61000-4-5 |
| Rth(j-c) | 1.5 °C/W - Enables efficient heatsink coupling; 12 A operation achievable with modest thermal interface |
| VTM (max) | 1.5 V - Low conduction loss (<18 W at 12 A) reduces thermal stress in sealed appliance enclosures |
Pinout & Package
ACST12-7CT uses the TO-220AB package (JEDEC MS-001AC), featuring isolated metal tab for direct heatsink mounting and screw torque specification of 0.4–0.6 N·m. The package meets UL94 V0 flammability rating and supports lead-free reflow soldering per JEDEC JESD97.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COM | Common terminal (MT1) | Main terminal 1 reference node; connected to neutral or low-side AC line in phase-control topologies |
| OUT | Output terminal (MT2) | Main terminal 2; carries full load current to AC load; electrically symmetric with COM for bidirectional conduction |
| G | Gate | Control input triggering conduction in all quadrants; referenced to COM; requires ≤35 mA pulse for turn-on |
Key Features
| Feature | Design Value |
|---|---|
| Integrated overvoltage crowbar | Clamps transients to 850 V and safely conducts surge energy through load-eliminates need for external MOVs or TVS diodes |
| Snubberless inductive switching | Supports direct driving of universal motors and compressors up to 12 A RMS without RC snubber network |
| High dV/dt immunity | 2000 V/µs minimum ensures reliable blocking under EFT noise, reducing false-trigger risk in noisy industrial environments |
| MCU-compatible gate drive | IGT ≤35 mA allows direct connection to 3.3 V/5 V microcontroller outputs via single series resistor (e.g., 330 Ω) |
| Planar TRIAC technology | Delivers stable off-state leakage (<1.5 mA at 125 °C) and long-term reliability in sealed, thermally constrained appliances |
Applications
| Washing Machine Drum Motor Control | Refrigerator Compressor Drive |
|---|---|
Use Scenario: Precise speed and direction control of universal AC motors in front-load washers using phase-angle or burst-fire switching. IC Role / Device Role / Timing Role: AC power switch acting as main load path controller; handles 12 A inrush and continuous torque currents with zero-crossing synchronized firing. Use Value: Eliminates external snubber and MOV, reducing BOM count by ≥3 passive components while meeting IEC 61000-4-5 surge immunity. | Use Scenario: Start-run switching and overload protection for hermetic compressors in domestic refrigeration systems. IC Role / Device Role / Timing Role: High-reliability AC mains switch managing compressor startup surges (up to 120 A peak) and steady-state run current. Use Value: Withstands compressor inrush-induced line transients without latch-up or failure, extending system lifetime beyond 10,000 cycles. |
| Air Conditioner Fan & Pump Control | Industrial AC Heater Sequencing |
Use Scenario: Duty-cycle modulated control of PSC or shaded-pole fans and condensate pumps in split-system AC units. IC Role / Device Role / Timing Role: Solid-state relay replacement handling 8–12 A resistive/inductive loads with precise on/off timing and thermal stability. Use Value: 1.5 °C/W junction-to-case thermal resistance enables compact heatsink integration in space-constrained HVAC control boards. | Use Scenario: Sequential energization of multiple 1200–2400 W heating elements in programmable industrial ovens and dryers. IC Role / Device Role / Timing Role: High-current AC switching element rated for repetitive 12 A RMS with guaranteed turn-off at zero-crossing. Use Value: Self-clamping behavior prevents voltage overshoot during element de-energization, protecting upstream triac drivers and isolation circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar AC power switching applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ACST10-7CT | 10 A RMS rating, identical 700 V VDRM and 2000 V/µs dV/dt, but lower ITSM (105 A vs. 120 A) | Suitable for ≤10 A loads (e.g., smaller fans, solenoids); not rated for 12 A compressor inrush | Select when load current is consistently ≤10 A and thermal margin is available |
| ACS108-7SN | 8 A RMS, 700 V, lower IGT (≤10 mA), but only 500 V/µs dV/dt and no crowbar clamping | Lacks self-protection against IEC 61000-4-5 surges; requires external MOV and snubber for same applications | Choose only if gate drive sensitivity is primary concern and external protection is acceptable |
Compared with ACST10-7CT and ACS108-7SN, the ACST12-7CT uniquely combines 12 A current capability, 2 kV/µs noise immunity, and integrated crowbar clamping-making it the only option among the three that satisfies snubberless, surge-robust operation for full-size appliance motors.
Availability
ACST12-7CT is available at Aetrix Electronics and suitable for washing machine motor control, refrigerator compressor drive, and HVAC fan sequencing requiring stable component supply, long-lifecycle support, and traceable sourcing for high-volume appliance manufacturing.
Supply support for ACST12-7CT 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, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.
The ACST/ACST12 product line targets appliance-grade AC power control, emphasizing intrinsic surge resilience, snubberless inductive load handling, and direct MCU interfacing-addressing reliability and BOM reduction in cost-sensitive white goods.
FAQ
What is the maximum allowable gate resistor value for reliable triggering with a 5 V MCU output?
A 330 Ω resistor limits gate current to ~12 mA when driven from 5 V, well below the 35 mA IGT max and within the 0.1 W average gate power limit. This value ensures robust triggering across temperature and process variation while avoiding gate overcurrent during fast transients.
Can ACST12-7CT replace a standard TRIAC in an existing design without layout changes?
Yes-if the existing design uses a TO-220AB TRIAC with COM–OUT–G pinout (e.g., BT139-800), ACST12-7CT is pin-compatible and offers superior dV/dt immunity and built-in surge protection. No PCB change is needed, though external MOVs may be removed to realize BOM savings.
Does the crowbar function activate during normal zero-crossing switching?
No-the crowbar only triggers during overvoltage events exceeding VCL (850 V), typically caused by lightning-induced surges or inductive kickback. During normal operation, it behaves identically to a standard TRIAC with clean turn-on/turn-off at controlled phase angles or zero crossings.
What thermal interface material is recommended for TO-220AB mounting?
Use a thermally conductive silicone pad (e.g., 1.0 mm thick, 1.5 W/m·K) or non-silicone thermal grease (0.5–1.0 W/m·K) between the isolated metal tab and aluminum heatsink. Torque mounting screw to 0.5 N·m to ensure Rth(j-c) remains ≤1.5 °C/W without mechanical stress on the die.
ACST12-7CT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Tube
- Product Status:
- Obsolete
- Triac Type:
- Standard
- 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):
- 35 mA
- Current - Hold (Ih) (Max):
- 50 mA
- Configuration:
- Single
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220
ACST12-7CT FAQ
1.How can I place an order for ACST12-7CT through Aetrix?
Please submit a Request for Quotation (RFQ) for ACST12-7CT 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 ACST12-7CT reliable?
The price and inventory of ACST12-7CT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ACST12-7CT is usually 5 days.
3.What payment methods are accepted for ACST12-7CT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ACST12-7CT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ACST12-7CT?
ACST12-7CT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ACST12-7CT 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 ACST12-7CT?
For technical support, including ACST12-7CT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ACST12-7CT requirements.
6.How does Aetrix verify that ACST12-7CT is sourced from the original manufacturer or authorized distributors?
All ACST12-7CT 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 ACST12-7CT meets industry standards.
7.What is the process for return or replacement of ACST12-7CT?
All ACST12-7CT units undergo pre-shipment inspection (PSI). If there is an issue with ACST12-7CT, 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 ACST12-7CT part is unused and in its original packaging.
Return procedure for ACST12-7CT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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