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Home > Products > Discrete Semiconductor Products > Thyristors > TRIACs

STMicroelectronics T435-800T

Name: T435-800T
Brand: STMicroelectronics
SKU: T435-800T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: T435-800T

Manufacturer:: STMicroelectronics

Category:: TRIACs

Package:: TO-220-3

Datasheet:: T435-800T.pdf

Description:: TRIAC ALTERNISTOR 800V 4A TO220

Quantity:: RFQ Add To RFQ list

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Inventory:145

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Product details

Overview

T435-800T from STMicroelectronics is a 4 A, 800 V snubberless three-quadrant triac in TO-220AB package, designed for robust AC phase control in inductive loads. It delivers 35 mA max gate trigger current (IGT), 400 V/µs dV/dt immunity at 125 °C, and 30 A non-repetitive surge capability - enabling reliable switching in universal motor drives and kitchen appliance power stages.

For engineers reviewing the T435-800T datasheet, T435-800T pinout, T435-800T application, or T435-800T equivalent, key selection criteria include snubberless commutation performance, 800 V blocking voltage, TO-220AB thermal resistance (R_th(j-c) = 2.6 °C/W), and compatibility with logic-level or pulse-triggered gate drive circuits.

Technical Context

The T435-800T employs ST's Snubberless™ logic-level triac architecture optimized for high dV/dt immunity (400 V/µs) and stable turn-off without external snubbers. Its three-quadrant operation restricts triggering to quadrants I, II, and III - eliminating false triggering from quadrant IV noise while maintaining full AC half-cycle control.

It features a low on-state voltage (V_TM ≤ 1.56 V at 5.5 A), dynamic resistance (R_d ≤ 120 mΩ), and thermal design support via R_th(j-c) = 2.6 °C/W - enabling direct heatsink mounting for sustained 4 A RMS conduction at T_c = 110 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DRM/V_RRM	800 V - blocks full AC line transients up to 800 V peak in both directions, suitable for 230 VAC mains with safety margin.
I_T(rms)	4 A - continuous RMS current rating at T_c = 110 °C, supports motor loads up to ~900 W resistive-equivalent.
I_GT	35 mA max - gate trigger current threshold enabling direct drive from microcontroller GPIO or optocoupler outputs.
dV/dt (min)	400 V/µs at 125 °C - prevents false turn-on during fast voltage transients in noisy inductive environments.
I_TSM	31 A at 60 Hz, 16.7 ms - withstands startup surges of universal motors and compressor loads without failure.
R_th(j-c)	2.6 °C/W - enables efficient thermal transfer to heatsink; allows 4 A operation with ≤10.4 °C junction-to-case rise at full load.
V_TM	≤1.56 V at 5.5 A - low conduction loss reduces self-heating and improves system efficiency in high-duty-cycle applications.

Pinout & Package

TO-220AB package with insulated tab (electrically isolated mounting surface), 3-pin through-hole configuration, lead-free and halogen-free epoxy molding per UL94 V0.

Pin/Terminal	Circuit Role	Design Meaning
A1 (MT1)	Main Terminal 1	Reference terminal for gate trigger; connected to neutral or low-side AC path in standard phase-control topology.
A2 (MT2)	Main Terminal 2	High-side AC line connection; carries full load current and defines polarity reference for quadrant-sensitive triggering.
G	Gate	Control input requiring ≥35 mA pulse to initiate conduction; compatible with zero-crossing or random-phase optotriac drivers.

Key Features

Feature	Design Value
Snubberless commutation	Eliminates need for external RC snubber networks in inductive loads - reducing BOM count and PCB area in motor control designs.
Three-quadrant operation	Blocks quadrant IV triggering - suppresses false turn-on from negative dV/dt on A2, improving noise immunity in EMI-prone appliances.
High dV/dt immunity	400 V/µs at 125 °C ensures stable blocking during fast transients from relay bounce or inductive kickback.
Logic-compatible gate	35 mA I_GT max allows direct interface with 5 V microcontrollers or standard optocouplers (e.g., MOC302x series).
Thermal robustness	R_th(j-c) = 2.6 °C/W and T_j range up to +125 °C support continuous operation in enclosed, thermally constrained environments.

Applications

Universal Motor Speed Control

Kitchen Appliance Power Switching

Use Scenario: Variable-speed control of brushed universal motors in power tools and vacuum cleaners using phase-angle dimming.

IC Role / Device Role / Timing Role: Main AC power switch triggered by zero-crossing synchronized gate pulses to regulate RMS voltage applied to motor winding.

Use Value: Snubberless operation eliminates snubber losses and component stress during high-dI/dt motor commutation events.

Use Scenario: On/off and power-level control of heating elements and motorized functions in dishwashers and blenders.

IC Role / Device Role / Timing Role: High-reliability AC load switch activated by microcontroller-driven optocoupler for isolation and timing precision.

Use Value: 800 V V_DRM accommodates 230 VAC mains with surge margin; TO-220AB package enables secure mechanical mounting and thermal management.

Electrovalve Actuation

Small Home Appliance Fan Control

Use Scenario: Duty-cycle modulated switching of solenoid valves in washing machine water inlet systems.

IC Role / Device Role / Timing Role: Fast-turning triac delivering precise 50/60 Hz half-cycle gating to control average solenoid current and force.

Use Value: 35 mA I_GT and 400 V/µs dV/dt ensure clean turn-on despite inductive flyback and line noise in shared appliance PCBs.

Use Scenario: Low-noise speed regulation of shaded-pole or PSC fans in air purifiers and dehumidifiers.

IC Role / Device Role / Timing Role: Phase-controlled AC switch placed between rectifier and fan motor to adjust effective voltage without audible buzz.

Use Value: Three-quadrant operation prevents erratic behavior during zero-crossing transitions, ensuring smooth fan ramp-up/down.

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
BT139-800	4 A, 800 V, 50 mA I_GT, standard four-quadrant triac, higher gate drive requirement.	Lacks snubberless design; requires external snubber for inductive loads; lower dV/dt immunity (100 V/µs).	Select when cost sensitivity outweighs snubber BOM reduction and noise immunity needs.
T435-800B	Identical electrical specs but in DPAK package; R_th(j-c) = 2.6 °C/W same, but R_th(j-a) = 70 °C/W vs 60 °C/W for TO-220AB.	Suitable for SMT assembly; requires PCB copper area for thermal relief; less mechanical robustness than TO-220AB.	Select for automated assembly where board space and reflow compatibility are prioritized over field-serviceable mounting.

Compared with BT139-800, T435-800T offers superior noise immunity and snubberless operation for inductive loads; compared with T435-800B, it provides better mechanical stability, easier heatsinking, and higher ambient thermal tolerance in enclosed enclosures.

Availability

T435-800T is available at Aetrix Electronics and suitable for universal motor control, electrovalve actuation, and small home appliance power switching requiring stable component supply across industrial production cycles.

Supply support for T435-800T 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, analog, MCU, and sensor technologies for industrial, automotive, and consumer markets.

The T4 series triacs are part of ST's high-reliability AC power switching portfolio, engineered specifically for snubberless operation in inductive AC loads such as universal motors and solenoids in white goods and power tools.

FAQ

Is T435-800T compatible with zero-crossing optocouplers like MOC3041?

Yes - T435-800T's 35 mA maximum I_GT is fully compatible with the 100 mA peak output of MOC3041 and similar zero-crossing optocouplers. Its snubberless design ensures clean turn-on even with the delayed gate pulse timing inherent in zero-crossing drivers, avoiding misfiring during voltage transitions.

What is the minimum heatsink requirement for continuous 4 A RMS operation?

At T_c = 110 °C and I_T(rms) = 4 A, junction temperature remains within limit if heatsink thermal resistance (R_th(c-s) + R_th(s-a)) keeps case-to-ambient rise ≤ 40 °C. With R_th(j-c) = 2.6 °C/W, a 15 °C/W extruded aluminum heatsink is sufficient for typical enclosure ambient conditions (≤50 °C).

Can T435-800T replace T435-600T in a 230 VAC design?

Yes - the 800 V V_DRM rating exceeds the 600 V version while maintaining identical I_T(rms), I_GT, and package. It provides enhanced surge margin against line transients and aging effects, with no circuit or layout changes required. Derating is unnecessary for standard 230 VAC ±10% mains.

Does T435-800T require a gate resistor? If so, what value?

A gate resistor is recommended to limit peak I_G and damp ringing. For optocoupler drive (e.g., MOC3023), 100–330 Ω ensures I_G stays below 4 A peak (per datasheet I_GM limit) while preserving fast turn-on. Lower values improve noise immunity; higher values risk marginal triggering under low-temperature or aged conditions.

T435-800T 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):: 4 A

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

Current - Non Rep. Surge 50, 60Hz (Itsm):: 30A, 31A

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

Current - Hold (Ih) (Max):: 35 mA

Configuration:: Single

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

T435-800T FAQ

1.How can I place an order for T435-800T through Aetrix?

Please submit a Request for Quotation (RFQ) for T435-800T 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 T435-800T reliable?

The price and inventory of T435-800T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for T435-800T is usually 5 days.

3.What payment methods are accepted for T435-800T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for T435-800T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for T435-800T?

T435-800T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your T435-800T 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 T435-800T?

For technical support, including T435-800T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your T435-800T requirements.

6.How does Aetrix verify that T435-800T is sourced from the original manufacturer or authorized distributors?

All T435-800T 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 T435-800T meets industry standards.

7.What is the process for return or replacement of T435-800T?

All T435-800T units undergo pre-shipment inspection (PSI). If there is an issue with T435-800T, 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 T435-800T part is unused and in its original packaging.

Return procedure for T435-800T:

1.Submit a request within 90 days.

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

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