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Home > Products > Discrete Semiconductor Products > Thyristors > TRIACs

STMicroelectronics T1235T-8I

Name: T1235T-8I
Brand: STMicroelectronics
SKU: T1235T-8I
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: T1235T-8I

Manufacturer:: STMicroelectronics

Category:: TRIACs

Package:: TO-220-3

Datasheet:: T1235T-8I.pdf

Description:: TRIAC ALTERNSTR 800V 12A TO220AB

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Product details

Overview

T1235T-8I from STMicroelectronics is a 12 A, 800 V Snubberless™ Triac in a TO-220AB insulated package, designed for high-commutation AC line switching in three-quadrant operation. It delivers 900 V non-repetitive surge capability (VDSM/VRSM), 2.5 kV RMS insulation (UL1557 certified), and operates up to 150 °C junction temperature - enabling robust motor control and heating applications without external snubber circuits.

For engineers reviewing the T1235T-8I datasheet, T1235T-8I pinout, T1235T-8I application, or T1235T-8I equivalent, key selection criteria include static dV/dt immunity (≥1000 V/µs at 150 °C), critical turn-off commutation (dl/dt)c (≥6 A/ms at 150 °C), gate trigger current (35 mA max), thermal resistance (Rth(j-c) = 2.6 °C/W), and UL94 V0 / ECOPACK®2 compliance.

Technical Context

This triac supports phase-angle and on/off AC control in mains-powered systems where high dv/dt immunity prevents false triggering during voltage transients. Its three-quadrant operation eliminates gate sensitivity in QIV, improving reliability in asymmetric load environments like universal motor drives.

The built-in ceramic insulation enables direct heatsink mounting with 2.5 kV RMS isolation, while the Snubberless™ architecture allows elimination of RC snubbers when operating within specified dV/dt and dl/dt limits - reducing BOM count and board space in home appliance and industrial controls.

Key Specifications

Parameter	Value and Actual Design Meaning
IT(RMS)	12 A - Continuous RMS current handling at Tc = 114 °C, suitable for 1.5 kW resistive loads at 120 VAC.
VDRM/VRRM	800 V at Tj = 125 °C - Peak repetitive blocking voltage defining safe AC line operation up to 565 V peak (400 VAC).
VDSM/VRSM	900 V - Non-repetitive surge rating supporting IEC 61000-4-5 Level 4 transient immunity (4 kV line-to-line).
(dl/dt)c	6 A/ms at Tj = 150 °C - Minimum commutation rate ensuring reliable turn-off in high-temperature motor control without snubber.
dV/dt	1000 V/µs at Tj = 150 °C - Static immunity preventing false turn-on during fast-rising noise on AC lines.
Rth(j-c)	2.6 °C/W - Junction-to-case thermal resistance enabling 4.6 W power dissipation at ΔT = 12 °C above case temperature.
IGT	35 mA max - Gate trigger current defining minimum driver strength required for reliable turn-on across all quadrants.

Pinout & Package

TO-220AB insulated package with electrically isolated metal tab (UL1557 certified, 2.5 kV RMS, UL94 V0 resin). Tab is internally connected to A2 and provides direct heatsink mounting without insulating hardware.

Pin/Terminal	Circuit Role	Design Meaning
A1	Anode 1	Main current terminal - referenced as cathode in QI/QII; forms bidirectional conduction path with A2.
A2	Anode 2	Main current terminal - internally bonded to insulated tab; serves as heatsink interface and circuit reference point.
G	Gate	Control input - triggers conduction in QI, QII, and QIII; insensitive in QIV due to three-quadrant design.

Key Features

Feature	Design Value
Snubberless™ operation	Eliminates external RC snubber when dV/dt < 20 V/µs and (dl/dt)c > 20 V/µs - reduces component count and layout complexity.
Ceramic-insulated tab	2.5 kV RMS isolation (UL1557 E81734) - enables direct mounting to grounded heatsinks without mica washers or silicone pads.
Three-quadrant triggering	Gate insensitive in QIV - improves noise immunity and simplifies gate drive design in single-supply control circuits.
High-temperature operation	150 °C max Tj - extends thermal margin in enclosed appliances and industrial enclosures without derating.
ECOPACK®2 compliance	Lead-free plating + halogen-free molding compound (UL94 V0) - meets RoHS and JEDEC MSL-1 requirements for automated assembly.

Applications

Motor Control

Heating Control

Use Scenario: Speed regulation of universal motors in vacuum cleaners and power tools using phase-angle dimming.

IC Role / Device Role / Timing Role: Bidirectional main switch controlling AC power delivery per half-cycle; gate triggered at variable conduction angle.

Use Value: High (dl/dt)c (12 A/ms at 125 °C) ensures clean turn-off during zero-crossing transitions, minimizing torque ripple and audible noise.

Use Scenario: On/off cycling of resistive heating elements in rice cookers and coffee makers.

IC Role / Device Role / Timing Role: Zero-voltage-switched (ZVS) AC line switch activated by microcontroller GPIO via optocoupler.

Use Value: 150 °C Tj rating allows sustained operation near hot surfaces; 2.5 kV isolation protects control logic from heater fault currents.

Lighting Dimming

Inrush Limiting

Use Scenario: Leading-edge dimming of incandescent and halogen lamps in residential lighting systems.

IC Role / Device Role / Timing Role: Phase-controlled AC switch synchronized to zero-crossing detection for smooth brightness adjustment.

Use Value: ≥2000 V/µs dV/dt at 125 °C prevents false triggering from EMI generated by TRIAC switching itself.

Use Scenario: Soft-start circuit limiting inrush current into transformer primary windings in HVAC control boards.

IC Role / Device Role / Timing Role: Delayed-turn-on switch bypassing NTC thermistor after warm-up; triggered once steady-state current is established.

Use Value: 95 A non-repetitive surge rating (tp = 16.7 ms) withstands transformer magnetizing inrush without degradation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar triac-based AC switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BTA12-800BWRG	12 A, 800 V, 4-pin TO-220 (non-insulated); lower dV/dt (1000 V/µs typ. at 25 °C), no UL1557 certification.	Requires external insulator for heatsink mounting; unsuitable for safety-critical Class I appliances.	Select when cost-sensitive and isolation can be implemented externally; verify creepage/clearance in final layout.
BTB12-800CW	12 A, 800 V, TO-220AB insulated; rated for 125 °C Tj only; (dl/dt)c = 10 A/ms at 125 °C (not specified at 150 °C).	Limited thermal headroom in sealed enclosures; may require derating above 125 °C ambient.	Prefer for legacy designs where 150 °C operation is not required; confirm thermal margin with Rth(j-a) = 60 °C/W.

Compared with BTA12-800BWRG and BTB12-800CW, the T1235T-8I uniquely combines UL1557-certified isolation, 150 °C operation, and guaranteed (dl/dt)c performance at elevated temperature - making it the only option qualified for compact, high-reliability, safety-regulated AC switching without snubbers.

Availability

T1235T-8I is available at Aetrix Electronics and suitable for motor control, heating, and lighting applications requiring stable component supply, long-term lifecycle support, and compliance with UL, RoHS, and halogen-free standards.

Supply support for T1235T-8I 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 intelligent power, analog, MEMS, and microcontroller solutions for industrial, automotive, and consumer markets.

The T1235T-8I belongs to ST's Snubberless™ Triac product line, engineered specifically for high-reliability AC power control in space-constrained, thermally demanding, and safety-certified applications such as white goods and building automation.

FAQ

Can T1235T-8I operate without a snubber circuit?

Yes - the T1235T-8I is explicitly designed as a Snubberless™ device. It can operate without an external RC snubber when dV/dt remains below 20 V/µs and (dl/dt)c exceeds 20 V/µs, as verified in ST's characterization data (Figure 11 and Table 3). This applies across its full 125–150 °C operating range.

What is the maximum recommended torque for mounting the TO-220AB insulated tab?

The manufacturer specifies a mounting torque of 0.4 to 0.6 N·m for the TO-220AB insulated package. Exceeding 0.6 N·m risks cracking the ceramic insulator or deforming the leadframe, compromising both thermal performance and 2.5 kV RMS isolation integrity.

Is T1235T-8I compliant with RoHS and REACH?

Yes - the T1235T-8I carries ECOPACK®2 certification, confirming lead-free plating and halogen-free molding compound compliant with RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. Full material declarations are available via ST's Product Change Notification system.

How does the three-quadrant architecture affect gate drive design?

The T1235T-8I's three-quadrant operation means the gate is insensitive in Quadrant IV (A2 negative, G positive), eliminating false triggering from capacitive coupling during negative half-cycles. This allows simpler unipolar gate drivers (e.g., MOC302x optocouplers) without bipolar biasing networks.

T1235T-8I Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: Snubberless™

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Active

Triac Type:: Alternistor - Snubberless

Voltage - Off State:: 800 V

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

Voltage - Gate Trigger (Vgt) (Max):: 1.3 V

Current - Non Rep. Surge 50, 60Hz (Itsm):: 95A, 90A

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

Current - Hold (Ih) (Max):: 40 mA

Configuration:: Single

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220AB Insulated

T1235T-8I FAQ

1.How can I place an order for T1235T-8I through Aetrix?

Please submit a Request for Quotation (RFQ) for T1235T-8I 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 T1235T-8I reliable?

The price and inventory of T1235T-8I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for T1235T-8I is usually 5 days.

3.What payment methods are accepted for T1235T-8I?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for T1235T-8I transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for T1235T-8I?

T1235T-8I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your T1235T-8I 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 T1235T-8I?

For technical support, including T1235T-8I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your T1235T-8I requirements.

6.How does Aetrix verify that T1235T-8I is sourced from the original manufacturer or authorized distributors?

All T1235T-8I 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 T1235T-8I meets industry standards.

7.What is the process for return or replacement of T1235T-8I?

All T1235T-8I units undergo pre-shipment inspection (PSI). If there is an issue with T1235T-8I, 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 T1235T-8I part is unused and in its original packaging.

Return procedure for T1235T-8I:

1.Submit a request within 90 days.

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

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