T435-400-D STMicroelectronics Triac A (Transistor Outline, Vertical) In Stock
STMicroelectronics T435-400-D is a sensitive-gate TRIAC rated at 4A and 400V for AC power switching in a through-hole TO package. It features a 35mA gate trigger current and 250V/µs dV/dt rating for reliable AC load control. Available from stock worldwide with fast delivery.
- Manufacturer
- STMicroelectronics
- Package
- Transistor Outline, Vertical
- Pin Count
- 3
- Lifecycle
- OBSOLETE
- Datasheet
- T435-400-D Datasheet PDF
- Category
- Triac A
- Temp Range
- -40.0°C to 125.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Sensitive gate design requiring only 35mA DC gate trigger current, enabling direct microcontroller or opto-coupler drive without additional gate amplification
- 400V off-state voltage and 4A RMS current rating suitable for 230V AC mains-connected resistive and inductive load switching applications
- 250V/µs minimum critical rate of rise of off-state voltage (dV/dt) ensuring stable operation in noisy industrial AC environments without false triggering
Applications
The T435-400-D is designed for AC power control in home appliances and industrial equipment where a microcontroller or opto-coupler must directly trigger a TRIAC to switch 230V mains-connected resistive loads up to 4A. Its sensitive gate reduces the required gate drive power, making it ideal for fan speed controllers, lamp dimmers, and heating element regulators driven from low-power microcontrollers. Engineers also use it in solid-state relay designs and motor soft-start circuits where the 400V blocking voltage and 35mA trigger sensitivity simplify the gate drive circuit and reduce BOM cost.
Specifications
| Reach Compliance Code | Unknown |
| YTEOL | 0 |
| Additional Feature | SENSITIVE GATE |
| Configuration | SINGLE |
| Critical Rate of Rise of Off-State Voltage-Min | 250V/us |
| DC Gate Trigger Current-Max | 35mA |
| DC Gate Trigger Voltage-Max | 1.5V |
| Holding Current-Max | 35mA |
| JESD-30 Code | R-PSFM-T3 |
| JESD-609 Code | e3 |
| Number of Elements | 1 |
| Package Body Material | PLASTIC/EPOXY |
| Package Shape | RECTANGULAR |
| Package Style | FLANGE MOUNT |
| Peak Reflow Temperature (Cel) | NOT SPECIFIED |
| Qualification Status | Not Qualified |
| RMS On-state Current-Max | 4A |
| Repetitive Peak Off-state Leakage Current-Max | 10 µA |
| Repetitive Peak Off-state Voltage | 400V |
| Surface Mount | NO |
| Terminal Finish | MATTE TIN |
| Terminal Form | THROUGH-HOLE |
| Terminal Position | SINGLE |
| Time@Peak Reflow Temperature-Max (s) | NOT SPECIFIED |
| Trigger Device Type | SNUBBERLESS TRIAC |
| Package | Transistor Outline, Vertical |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
No known alternates. Submit an RFQ and our team can suggest alternatives.
Frequently Asked Questions
What are the voltage and current ratings of T435-400-D and which AC loads can it switch at 230V mains?
T435-400-D is rated at 400V off-state voltage and 4A RMS current. At 230V AC mains, this translates to a maximum load power of approximately 920W for purely resistive loads. It is suitable for switching heating elements, incandescent lamps, and small AC fan motors up to 920W from a standard European 230V supply.
How sensitive is the gate trigger of T435-400-D, and can it be driven directly from a microcontroller GPIO?
T435-400-D requires a maximum DC gate trigger current of 35mA and gate trigger voltage of 1.5V to latch into conduction. A standard 3.3V MCU GPIO sourcing 35mA exceeds typical GPIO limits, so the recommended drive path is through a MOC3021 opto-coupler or a small NPN transistor buffer, limiting MCU GPIO current to under 10mA while providing the 35mA TRIAC gate drive.
For an industrial fan speed controller operating on 230V AC, how does T435-400-D's dV/dt rating protect against false triggering?
T435-400-D is rated at a minimum critical dV/dt of 250V/µs, meaning it can withstand transient voltage rise rates up to 250V/µs across its MT1-MT2 terminals without spuriously triggering. In industrial environments with switching transients from nearby contactors or variable-frequency drives, this 250V/µs rating combined with a snubber RC network (typically 100Ω and 10nF) prevents nuisance firing that could damage the controlled fan motor.
When is T435-400-D preferable to a standard gate TRIAC for a small appliance lamp dimmer design?
In a lamp dimmer using a DIAC-based phase-cutting trigger, the sensitive gate of T435-400-D allows the DIAC breakover voltage to be set lower, reducing the holding voltage on the trigger capacitor from about 32V to under 20V. This 35mA trigger sensitivity means the RC timing network can use smaller, lower-voltage capacitors, cutting BOM cost by eliminating the need for higher-voltage 400V-rated timing capacitors in designs under 200W.
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