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Home > Products > Discrete Semiconductor Products > Thyristors > TRIACs

STMicroelectronics ACST1235-8FP

Name: ACST1235-8FP
Brand: STMicroelectronics
SKU: ACST1235-8FP
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ACST1235-8FP

Manufacturer:: STMicroelectronics

Category:: TRIACs

Package:: TO-220-3 Full Pack

Datasheet:: ACST1235-8FP.pdf

Description:: TRIAC 800V 12A TO220FPAB

Quantity:: RFQ Add To RFQ list

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Inventory:1,728

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Product details

Overview

ACST1235-8FP from STMicroelectronics is a 12 A, 800 V overvoltage-protected AC switch built on A.S.D.® technology, integrating a triac with self-contained overvoltage clamping (V_CL ≥ 850 V) and rated for T_j = 150 °C. It replaces discrete triac + snubber + transient protection in motor control circuits, enabling direct drive of universal drum motors and compressor loads without external protection components.

For engineers reviewing the ACST1235-8FP datasheet, ACST1235-8FP pinout, ACST1235-8FP application, or ACST1235-8FP equivalent, key selection criteria include its 2 kV/µs static dV/dt immunity at 150 °C, I²t rating of 66 A²s, integrated crowbar-based surge protection compliant with IEC 61000-4-5, and TO-220FPAB insulated package with 1500 V_RMS isolation.

Technical Context

The ACST1235-8FP implements an integrated triac structure with monolithically embedded high-voltage clamping circuitry that triggers into conduction during line transients exceeding V_CL, dissipating energy through the load rather than requiring external MOVs or RC snubbers. Its gate trigger current is specified at 35 mA max across quadrants I–III at 25 °C, with latching current ≤ 40 mA and holding current ≤ 30 mA.

Thermal performance is defined by R_th(j–c) = 3.5 °C/W and maximum junction temperature of 150 °C, supporting continuous 12 A RMS operation at T_c = 97 °C. The device meets UL E81734 and complies with IEC 61000-4-4 and -4-5 immunity standards without auxiliary components.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DRM/V_RRM	800 V - blocks full sine-wave AC line voltages up to 565 V_peak with margin for transients
I_T(RMS)	12 A - supports continuous motor loads such as washing machine drum motors and fridge compressors
V_CL	≥ 850 V - clamps inductive turn-off spikes and absorbs IEC 61000-4-5 surges up to 2 kV peak
dV/dt (static)	2000 V/µs min @ 150 °C - prevents false triggering under fast-rising noise in noisy appliance environments
R_th(j–c)	3.5 °C/W - enables thermal design with heatsink mounting while maintaining T_j ≤ 150 °C at full load
I_GT	35 mA max - compatible with standard MCU GPIO or optocoupler drivers without gate amplification
V_TM	1.5 V max @ 17 A - low conduction loss reduces power dissipation and heatsink requirements

Pinout & Package

ACST1235-8FP uses the TO-220FPAB insulated package with creepage/clearance optimized for reinforced insulation (1500 V_RMS, 60 s), lead-free finish, and mounting torque of 0.4–0.6 N·m.

Pin/Terminal	Circuit Role	Design Meaning
G	Gate input	Controls switching; accepts 35 mA trigger current; compatible with standard logic-level drivers
COM	Common terminal (MT1)	Reference node for gate drive and load return; tied to neutral or low-side return path
OUT	Main output (MT2)	Carries full load current (12 A RMS); voltage referenced to COM defines blocking/clamping behavior

Key Features

Feature	Design Value
Integrated overvoltage protection	Self-triggering crowbar clamping (V_CL ≥ 850 V) eliminates need for external MOVs or snubbers in IEC 61000-4-5-compliant designs
High-temperature operation	Rated for continuous 12 A at T_j = 150 °C, enabling compact thermal design in sealed appliance enclosures
Enhanced commutation robustness	Withstands inductive load turn-off without snubber due to high (dI/dt)_c ≥ 6 A/ms @ 150 °C
UL-certified isolation	TO-220FPAB package certified to UL E81734 with 1500 V_RMS insulation, meeting safety requirements for Class II appliances
ECOPACK®2 compliance	Lead-free, RoHS-compliant construction with defined environmental grade per ST's ECOPACK® program

Applications

Washing Machine Drum Motor Control

Fridge/AC Compressor Drive

Use Scenario: Controlling universal (AC series) motors in washing machines during spin and wash cycles with bidirectional speed/torque regulation.

IC Role / Device Role / Timing Role: AC switch replacing mechanical relay or discrete triac+snubber; handles full 12 A RMS load with zero-crossing or phase-angle control.

Use Value: Eliminates snubber losses and component count; withstands repeated inrush currents and torque transients without derating.

Use Scenario: Driving hermetic compressors in refrigerators and air conditioners where high inrush (5–7× rated) and frequent start-stop cycles occur.

IC Role / Device Role / Timing Role: High-reliability AC power switch managing compressor on/off sequencing and soft-start via gate timing control.

Use Value: Integrated V_CL clamping absorbs turn-off energy from inductive kickback, preventing failure without external protection.

Resistive Load Dimming

Industrial Fan Speed Control

Use Scenario: Phase-controlled dimming of incandescent lamps or heating elements in smart home appliances and ovens.

IC Role / Device Role / Timing Role: Bidirectional AC switch operating in quadrants I, II, and III to enable leading-edge or trailing-edge dimming waveforms.

Use Value: 35 mA I_GT ensures compatibility with standard optotriac drivers; low V_TM minimizes heat generation at partial conduction.

Use Scenario: Variable-speed control of single-phase induction fans in HVAC systems and industrial enclosures.

IC Role / Device Role / Timing Role: Robust AC power switch handling 12 A RMS fan loads with high dV/dt immunity in electrically noisy plant environments.

Use Value: 2000 V/µs static dV/dt immunity at 150 °C prevents false triggering from EMI generated by nearby contactors or VFDs.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ACS108-8SN	Lower current rating (8 A RMS), same 800 V V_DRM, no integrated clamping - requires external snubber	Suitable only for <8 A resistive or lightly inductive loads; not recommended for compressor or universal motor drive	Select when cost sensitivity outweighs protection integration and thermal headroom is ample
ACST1035-8FP	Same package and protection architecture but rated for 10 A RMS and lower I²t (45 A²s vs. 66 A²s)	Acceptable for smaller drum motors or fans, but insufficient for high-inrush compressor applications	Choose for space-constrained designs where 10 A capacity suffices and BOM simplification remains critical

Compared with ACS108-8SN and ACST1035-8FP, the ACST1235-8FP delivers higher current capability, superior surge robustness (66 A²s), and guaranteed clamping performance - making it the only option qualified for full-power compressor and universal motor control without external protection.

Availability

ACST1235-8FP is available at Aetrix Electronics and suitable for washing machine motor control, refrigerator compressor drive, resistive dimming, and industrial fan speed regulation requiring stable component supply and long-term lifecycle support.

Supply support for ACST1235-8FP 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 microcontrollers, power devices, sensors, and analog ICs for industrial, automotive, and consumer markets.

The ACST™/ACST family targets appliance-grade AC power switching, combining triac functionality with integrated overvoltage protection to simplify safety-compliant motor control designs.

FAQ

What is the maximum continuous case temperature for reliable 12 A operation?

The datasheet specifies I_T(RMS) = 12 A at T_c = 97 °C under full sine-wave conditions. Operation above this temperature requires derating per Figure 3; sustained case temperatures beyond 97 °C reduce allowable RMS current to maintain T_j ≤ 150 °C and prevent thermal runaway.

Does ACST1235-8FP require a heat sink in typical appliance applications?

Yes - with R_th(j–c) = 3.5 °C/W and P_D ≈ 18 W at 12 A (based on V_TM = 1.5 V), a heatsink is mandatory to limit T_j to 150 °C. Typical designs use aluminum extrusions or stamped metal heatsinks mounted directly to the TO-220FPAB tab with thermal interface material.

Can ACST1235-8FP replace a standard triac in an existing design without layout changes?

No - although pin-compatible with standard TO-220 triacs, the ACST1235-8FP's integrated clamping alters surge response and gate drive timing margins. Layout must ensure adequate clearance for 1500 V_RMS isolation and avoid routing sensitive traces near the COM/OUT terminals where transient energy is dissipated.

How many IEC 61000-4-5 surges can ACST1235-8FP withstand before degradation?

The device is rated for ≥10 non-repetitive 2 kV surges (1.2/50 µs voltage, 8/20 µs current) per polarity, as verified in the test circuit of Figure 19. Each event causes temporary conduction but no parameter shift; recovery occurs automatically after the next zero-crossing, with no cumulative wear observed within specification limits.

ACST1235-8FP Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: ACS™/A.S.D®

Package/Case:: TO-220-3 Full Pack

Packaging:: Tube

Product Status:: Active

Triac Type:: Standard

Voltage - Off State:: 800 V

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

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

Current - Non Rep. Surge 50, 60Hz (Itsm):: 100A, 105A

Current - Gate Trigger (Igt) (Max):: 35 mA

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

Configuration:: Single

Operating Temperature:: -40°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220FPAB

ACST1235-8FP FAQ

1.How can I place an order for ACST1235-8FP through Aetrix?

Please submit a Request for Quotation (RFQ) for ACST1235-8FP 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 ACST1235-8FP reliable?

The price and inventory of ACST1235-8FP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ACST1235-8FP is usually 5 days.

3.What payment methods are accepted for ACST1235-8FP?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ACST1235-8FP transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ACST1235-8FP?

ACST1235-8FP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ACST1235-8FP 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 ACST1235-8FP?

For technical support, including ACST1235-8FP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ACST1235-8FP requirements.

6.How does Aetrix verify that ACST1235-8FP is sourced from the original manufacturer or authorized distributors?

All ACST1235-8FP 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 ACST1235-8FP meets industry standards.

7.What is the process for return or replacement of ACST1235-8FP?

All ACST1235-8FP units undergo pre-shipment inspection (PSI). If there is an issue with ACST1235-8FP, 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 ACST1235-8FP part is unused and in its original packaging.

Return procedure for ACST1235-8FP:

1.Submit a request within 90 days.

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

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