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Home > Products > Discrete Semiconductor Products > Thyristors > TRIACs

STMicroelectronics T405-400T

Name: T405-400T
Brand: STMicroelectronics
SKU: T405-400T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: T405-400T

Manufacturer:: STMicroelectronics

Category:: TRIACs

Package:: TO-220-3

Datasheet:: T405-400T.pdf

Description:: TRIAC SENS GATE 400V 4A TO220

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Inventory:5,955

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Product details

Overview

T405-400T from STMicroelectronics is a 4 A, 600 V three-quadrant logic-level triac in TO-220AB package, designed for AC phase control of inductive loads with low gate trigger current (5 mA max), high commutation robustness (dV/dt ≥ 20 V/µs at 125 °C), and Snubberless operation. It enables compact motor control in universal-motor-powered kitchen appliances and power tools.

For engineers reviewing the T405-400T datasheet, T405-400T pinout, T405-400T application, or T405-400T equivalent, key selection criteria include gate sensitivity (IGT ≤ 5 mA), blocking voltage (VDRM = 600 V), thermal resistance (Rth(j-c) = 2.6 °C/W), and snubberless commutation capability for inductive switching without external RC networks.

Technical Context

The T405-400T uses ST's Snubberless logic-level triac architecture, enabling reliable turn-on with minimal gate drive across all quadrants (I, II, III) and stable commutation under high dV/dt stress (≥20 V/µs at 125 °C). Its low IGT (5 mA max) and low holding current (IH ≤ 10 mA) support direct microcontroller GPIO driving without buffer stages.

It operates with full sine-wave RMS current up to 4 A at case temperature ≤110 °C, supported by junction-to-case thermal resistance of 2.6 °C/W. The device maintains latching current (IL ≤ 10 mA) and on-state voltage (VTM ≤ 1.56 V at 5.5 A) across –40 to +125 °C junction temperature range.

Key Specifications

Parameter	Value and Actual Design Meaning
IT(rms)	4 A - Sustains continuous AC load current in motor and solenoid applications without heatsink derating up to Tc = 110 °C.
VDRM / VRRM	600 V - Blocks line transients up to 600 V peak in 230 VAC systems with safety margin for surge events.
IGT (max)	5 mA - Compatible with 3.3 V/5 V MCU GPIO outputs; eliminates need for gate driver ICs or discrete transistor buffers.
dV/dt (min)	20 V/µs at 125 °C - Ensures reliable commutation during rapid voltage transients in inductive switching without snubber circuits.
VTM (max)	1.56 V at 5.5 A - Limits conduction loss to <8.6 W at full RMS current, reducing thermal design burden.
Rth(j-c)	2.6 °C/W - Enables direct mounting to chassis or small heatsink for thermal management in space-constrained appliances.
IH (max)	10 mA - Guarantees turn-off stability when load current falls below threshold, preventing unintended re-triggering.

Pinout & Package

TO-220AB package with insulated tab; standard 3-pin through-hole configuration. Tab is electrically connected to MT2 terminal. Mounting torque: 0.4–0.6 N·m.

Pin/Terminal	Circuit Role	Design Meaning
MT1 (Main Terminal 1)	Anode 1 / AC line return path	Primary current return node; referenced to gate for triggering; polarity-sensitive in quadrant I/III operation.
MT2 (Main Terminal 2)	Anode 2 / AC line input path	Connected to heatsink tab; carries full load current; defines reference for gate voltage and dV/dt stress.
G (Gate)	Trigger control input	Accepts low-energy pulse (5 mA max) to initiate conduction; requires no sustained drive; sensitive to noise due to logic-level threshold.

Key Features

Feature	Design Value
Snubberless commutation	Validated dV/dt ≥ 20 V/µs at 125 °C - eliminates external RC snubber components in motor control PCB layouts.
Logic-level gate drive	IGT ≤ 5 mA at 12 V - enables direct interface with 3.3 V/5 V microcontrollers and logic ICs without level-shifting.
Three-quadrant operation	Triggers reliably in quadrants I, II, and III - supports phase-angle control in both half-cycle polarities for universal AC loads.
High thermal efficiency	Rth(j-c) = 2.6 °C/W - allows >3 W dissipation with ≤10 °C rise above heatsink, simplifying thermal design in sealed enclosures.
Robust transient immunity	ITSM = 30 A (50 Hz, 20 ms) - withstands startup surges in universal motors and compressor loads without failure.

Applications

Kitchen Appliance Motor Control

Power Tool Speed Regulation

Use Scenario: Variable-speed control of universal motors in blenders, food processors, and dishwashers using phase-cut AC dimming.

IC Role / Device Role / Timing Role: Main AC power switch; triggered synchronously with zero-crossing detection to adjust conduction angle per half-cycle.

Use Value: Eliminates mechanical speed controls; enables precise RPM tuning with <5 mA gate drive and no snubber components.

Use Scenario: Bidirectional speed control in corded drills and sanders where motor direction is fixed but torque must be modulated.

IC Role / Device Role / Timing Role: High-current AC switch in phase-control topology; handles repetitive 30 A surge peaks during stall conditions.

Use Value: Withstands 30 A non-repetitive surges and maintains stable commutation at 125 °C junction temperature during extended use.

Electrovalve Actuation

Small HVAC Fan Control

Use Scenario: On/off and proportional control of 230 VAC solenoid valves in washing machines and irrigation systems.

IC Role / Device Role / Timing Role: Zero-voltage-switched AC switch; driven by microcontroller PWM with gate timing aligned to AC phase.

Use Value: Low IH (≤10 mA) ensures clean turn-off after coil de-energization; high dV/dt immunity prevents false triggering from coil flyback.

Use Scenario: Energy-efficient airflow regulation in residential air purifiers and compact HVAC units using shaded-pole or PSC motors.

IC Role / Device Role / Timing Role: Line-synchronized triac switch operating at 50/60 Hz; manages RMS voltage delivered to motor windings.

Use Value: 600 V blocking rating accommodates 230 VAC mains with 1.5× safety margin; TO-220AB package enables direct heatsink mounting in confined duct spaces.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ST T410-600T	Higher IGT (10 mA max); identical VDRM, package, and thermal specs.	Requires stronger gate drive; less suitable for direct MCU GPIO interface without buffering.	Select when higher gate noise immunity is needed or when existing designs use 10 mA drive capability.
Littelfuse Q4004L4	4 A/400 V rating; lower blocking voltage; TO-220 package; IGT = 35 mA.	Not suitable for 230 VAC systems requiring 600 V margin; needs gate driver stage.	Consider only for 120 VAC legacy designs where 400 V rating suffices and higher IGT is acceptable.

Compared with T410-600T and Q4004L4, the T405-400T uniquely delivers 600 V blocking with 5 mA gate sensitivity in TO-220AB, enabling simpler, lower-BOM-cost motor control in 230 VAC appliances without compromising surge or thermal performance.

Availability

T405-400T is available at Aetrix Electronics and suitable for kitchen appliance motor control, power tool speed regulation, electrovalve actuation, and small HVAC fan control requiring stable component supply across long-lifecycle consumer electronics programs.

Supply support for T405-400T 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, MEMS, and microcontroller 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, logic-level phase control in cost-sensitive, thermally constrained inductive load applications.

FAQ

Is T405-400T compatible with 3.3 V microcontroller GPIOs?

Yes. With maximum gate trigger current of 5 mA at 12 V and guaranteed operation down to 5 V, the T405-400T can be directly driven by most 3.3 V MCUs using a series resistor (e.g., 220 Ω) to limit peak gate current to <4 mA while maintaining reliable turn-on across temperature.

Does T405-400T require a heatsink in 4 A continuous operation?

Yes. At 4 A RMS and Tc = 110 °C, junction temperature reaches ~125 °C with Rth(j-c) = 2.6 °C/W. A minimum heatsink (e.g., 10 cm² aluminum plate) is required to maintain safe operating temperature; ambient-only operation exceeds thermal limits.

Can T405-400T replace older BT136 or MAC12A8 triacs?

No direct drop-in replacement. While pin-compatible in TO-220AB, T405-400T has lower IGT (5 mA vs. 15–50 mA), higher dV/dt immunity (20 V/µs vs. 10 V/µs), and Snubberless design - requiring gate drive and layout review to avoid false triggering or overdrive.

What is the maximum allowable gate pulse width for reliable triggering?

Gate pulses must exceed 10 µs to ensure latching; typical recommended width is 20–100 µs. Shorter pulses risk incomplete turn-on, especially at low junction temperatures or high dV/dt stress. Pulse energy must stay below PG(AV) = 1 W average limit.

T405-400T Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Triac Type:: Logic - Sensitive Gate

Voltage - Off State:: 400 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):: 5 mA

Current - Hold (Ih) (Max):: 10 mA

Configuration:: Single

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

T405-400T FAQ

1.How can I place an order for T405-400T through Aetrix?

Please submit a Request for Quotation (RFQ) for T405-400T 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 T405-400T reliable?

The price and inventory of T405-400T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for T405-400T is usually 5 days.

3.What payment methods are accepted for T405-400T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for T405-400T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for T405-400T?

T405-400T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your T405-400T 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 T405-400T?

For technical support, including T405-400T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your T405-400T requirements.

6.How does Aetrix verify that T405-400T is sourced from the original manufacturer or authorized distributors?

All T405-400T 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 T405-400T meets industry standards.

7.What is the process for return or replacement of T405-400T?

All T405-400T units undergo pre-shipment inspection (PSI). If there is an issue with T405-400T, 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 T405-400T part is unused and in its original packaging.

Return procedure for T405-400T:

1.Submit a request within 90 days.

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

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