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Home > Products > Discrete Semiconductor Products > Thyristors > TRIACs

STMicroelectronics T1235T-8FP

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

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Part No.:: T1235T-8FP

Manufacturer:: STMicroelectronics

Category:: TRIACs

Package:: TO-220-3 Full Pack

Datasheet:: T1235T-8FP.pdf

Description:: TRIAC ALTERNSTR 800V 12A TO220AB

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Product details

Overview

T1235T-8FP from STMicroelectronics is a snubberless, three-quadrant triac rated for 12 A RMS on-state current, 800 V repetitive peak off-state voltage (VDRM/VRRM), and 35 mA maximum gate trigger current (IGT). It operates across -40 °C to +150 °C junction temperature, features 2 kV rms insulation rating, and is designed for AC line switching in motor control, lighting, and inrush limiting where high commutation robustness is required without external snubbers.

For engineers reviewing the T1235T-8FP datasheet, T1235T-8FP pinout, T1235T-8FP application, or T1235T-8FP equivalent, key selection criteria include dI/dt capability (100 A/µs), (dI/dt)_c (12 A/ms at 125 °C), V_GT (≤1.3 V), thermal resistance R_th(j-c) (3.5 °C/W), and UL certification (File E81734) for safety-critical AC power control.

Technical Context

This triac supports full-cycle AC phase-angle and on/off control in three-quadrant operation (Quadrants I, II, III), enabling gate triggering with either polarity of A2 relative to A1. Its Snubberless™ architecture eliminates need for external RC snubbers when operated within specified dV/dt (≥2000 V/µs at 125 °C) and (dI/dt)_c limits.

It delivers 1.55 V max on-state voltage (V_T) at 17 A and 25 °C, with dynamic resistance (R_d) ≤37 mΩ at 150 °C, ensuring low conduction loss in thermally constrained designs. Insulation rating of 2 kV rms and ECOPACK®2 compliance support industrial and appliance-grade safety and environmental requirements.

Key Specifications

Parameter	Value and Actual Design Meaning
IT(rms)	12 A - Sustained AC load current handling at Tc = 99 °C, suitable for continuous motor or heater drive.
VDRM / VRRM	800 V - Peak repetitive blocking voltage at 125 °C, compatible with 230 VAC mains with margin.
IGT (max)	35 mA - Maximum gate trigger current required, enabling direct drive from microcontrollers or optocouplers with minimal buffer.
(dI/dt)c	12 A/ms at 125 °C - Critical rate of current decrease before commutation failure; enables reliable turn-off under inductive loads.
Rth(j-c)	3.5 °C/W - Junction-to-case thermal resistance; allows ~3.4 W dissipation at 12 A with 12 °C case-to-ambient rise.
Vins	2 kV rms - Certified isolation voltage for 1 minute, meeting reinforced insulation requirements per UL E81734.

Pinout & Package

Package: TO-220FPAB - insulated, lead-free, full-pack through-hole housing with isolated heatsink tab (A2 connected to tab), 2.0 g weight, 0.4–0.6 N·m mounting torque recommendation.

Pin/Terminal	Circuit Role	Design Meaning
A1	Main Terminal 1	Anode 1 - primary current path input; referenced as common for gate trigger in Q1/Q2; electrically isolated from heatsink tab.
A2	Main Terminal 2	Anode 2 - main current return; internally connected to metal tab/heatsink; must be electrically isolated from PCB ground unless system design permits.
G	Gate	Control terminal - triggers conduction when ≥IGT applied between G and A1; functional in all three quadrants (I, II, III).

Key Features

Feature	Design Value
Snubberless operation	Validated up to 2000 V/µs dV/dt and 12 A/ms (dI/dt)c - eliminates RC snubber components, reducing BOM count and board space in AC switching stages.
Three-quadrant triggering	Functional gate sensitivity in Quadrants I, II, and III - simplifies driver design by accepting gate pulses of either polarity relative to A1.
UL-certified insulation	2 kV rms isolation (File E81734) - satisfies end-equipment safety standards for Class I appliances and industrial controls without additional barrier design.
High commutation robustness	(dI/dt)c = 12 A/ms at 125 °C - ensures reliable turn-off under highly inductive loads like universal motors or solenoids without false re-triggering.

Applications

Motor Control Circuits

Lighting Control

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

IC Role / Device Role / Timing Role: Main AC power switch controlling RMS voltage delivered to motor windings via leading-edge phase control.

Use Value: Eliminates snubber network while sustaining >100 A surge current (ITSM = 95 A @ 60 Hz), extending motor life and reducing EMI.

Use Scenario: Dimmable LED driver input stage or incandescent lamp switching in smart home wall switches.

IC Role / Device Role / Timing Role: Zero-crossing or phase-controlled AC line switch enabling smooth brightness adjustment.

Use Value: 35 mA IGT allows direct optocoupler drive (e.g., MOC3021), and 800 V VDRM supports global 230/120 VAC operation.

Small Home Appliances

Inrush Current Limiting

Use Scenario: On/off control of heating elements in coffee makers, rice cookers, and fryers.

IC Role / Device Role / Timing Role: High-reliability AC load switch activated by microcontroller GPIO via discrete transistor or opto-isolator.

Use Value: 12 A IT(rms) and 3.5 °C/W Rth(j-c) enable compact heatsinking; ECOPACK®2 compliance meets RoHS/REACH requirements.

Use Scenario: Soft-start circuit for transformer-based power supplies or large capacitive inputs.

IC Role / Device Role / Timing Role: Inrush limiter bypassed after delay, using triac to short NTC or series resistor once steady state is reached.

Use Value: 900 V VRSM withstands transient overvoltages during cold-start; 2 kV insulation prevents creepage/clearance failures.

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
BTB12-800CW	Same 12 A/800 V rating but 50 mA IGT (higher gate drive requirement); TO-220AB package (non-insulated tab).	Lacks UL certification and 2 kV insulation; requires external isolation for safety-critical use.	Select only if cost-sensitive and isolation handled externally; not drop-in for safety-certified designs.
Q6012LH5	12 A/600 V rating; 50 mA IGT; 3-quadrant; UL recognized (E170223) but lower VDRM limits 120 VAC-only use.	Lower blocking voltage restricts use to 120 VAC systems; higher IGT demands stronger gate drivers.	Prefer for North American 120 VAC appliances where 600 V margin suffices and UL recognition is sufficient.

Compared with BTB12-800CW and Q6012LH5, the T1235T-8FP offers superior dV/dt immunity (2000 V/µs), certified 2 kV insulation, and lower gate drive demand (35 mA), making it optimal for globally rated, safety-compliant, snubberless 230 VAC applications.

Availability

T1235T-8FP is available at Aetrix Electronics and suitable for motor control circuits, lighting dimmers, and small home appliance power stages requiring stable component supply, long-term lifecycle support, and UL-certified reliability.

Supply support for T1235T-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, specializing in power management, analog, MCU, and discrete devices for industrial, automotive, and consumer markets.

The T1235T-8FP belongs to ST's Snubberless™ Triac product line, engineered specifically for robust, simplified AC power control in cost-sensitive, safety-regulated appliances and industrial equipment.

FAQ

Is the T1235T-8FP compatible with zero-crossing trigger circuits?

No - the T1235T-8FP is optimized for phase-angle control and high dI/dt commutation, not zero-crossing operation. Its three-quadrant gate structure supports triggering at any point in the AC cycle, but it lacks integrated zero-crossing detection. External zero-crossing sensing (e.g., using an optocoupler like H11AA1) is required if synchronous switching is needed.

Can the metal tab (A2) be directly mounted to a grounded heatsink?

No - the TO-220FPAB package has an insulated tab connected to A2, but insulation is rated for 2 kV rms only. Direct mounting to a grounded heatsink violates creepage/clearance requirements unless the heatsink itself is fully isolated and rated for reinforced insulation. Use insulating pads and shoulder washers, and verify system-level dielectric testing.

What is the minimum gate trigger pulse width required for reliable turn-on?

The datasheet specifies IGM = 4 A peak gate current with tp = 20 µs. For reliable triggering across temperature and manufacturing variation, ST recommends ≥100 µs pulse width at ≥1.5× IGT (i.e., ≥52.5 mA) to ensure latching under worst-case conditions, especially at high junction temperatures where IGT rises.

Does the "T" in T1235T-8FP indicate a specific temperature grade?

Yes - the "T" denotes enhanced commutation performance: higher (dI/dt)c (12 A/ms vs. standard 8 A/ms) and improved dV/dt immunity (2000 V/µs at 125 °C), achieved via optimized silicon structure. It is not a separate temperature grade but a performance variant within the same -40 °C to +150 °C operating range.

T1235T-8FP Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: Snubberless™

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

Packaging:: Tube

Product Status:: Obsolete

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):: 90A, 95A

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

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

Configuration:: Single

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220FPAB

T1235T-8FP FAQ

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

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

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

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

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

Note: Certain payment methods may incur a processing fee.

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

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

Once your T1235T-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 T1235T-8FP?

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

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

All T1235T-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 T1235T-8FP meets industry standards.

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

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

Return procedure for T1235T-8FP:

1.Submit a request within 90 days.

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

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