A very compact solution for switching loads on AC power lines

Not limited by electromechanical ageing contingencies, triacs have a very long lifespan within circuits fully respecting specification boundaries.


With a voltage range from 600 to 800 V and up to 1200 V for certain industrial devices, ST's portfolio covers medium-power AC loads with 1 to 50 A triacs. 

With a range of driveable AC loads from 120 to 500 V, the list of circuits benefiting from ST triacs includes dimmers, all types of AC mains on-off switches, home or office copy/printer appliances, as well as industrial motor starters or SSRs, gardening tools, automated irrigation systems and a wide variety of automation controllers for factories, buildings and homes:

  • The high-voltage triacs are dedicated to industrial and three-phase mains switching applications.
  • Designed to ensure high switching performance in circuits that need space optimization, our 8T triacs are ideal for applications with high EMI constraints while our 6H triacs and 8H triacs target applications with high thermal constraints
  • Our standard and snubberless™ triacs retain the exhaustive gate drive possibilities and packages covering all power mains on/off and phase angle switching needs.
  • Featuring overvoltage protection functions, our ACS™ AC switches include highly inductive load switching capabilities for home and irrigation appliances including solenoid actuators and pumps, while our ACST triacs are designed for higher loads in appliances or equipment plugged in 24/7.

Triacs belong to our STPOWER family.

Ease your transition to surface-mount Triacs with our extended D²PAK portfolio

ST further extends its D²PAK offer for Triacs, ideal for compact designs. With parts ranging from 8 to 30 A, this Triac D²PAK offer is particularly suited for home and factory automation, allowing innovative designs with isolated metal substrate (IMS) and direct-bonded copper boards.
Discover our High-temperature Triacs and Standard and Snubberless Triacs in D²PAK.

800 V T-series triacs outrun competition for load control

800 V T-series high-performance triacs are designed for AC loads in industrial control and home appliances, enabling innovative and safe AC load control. With immunity (dV/dt) up to twice as high and commutation capability (dI/dt)c up to 5 times as good as state-of-art Triacs, this high-performance 800 V T-series triacs enables circuits to be more robust to EMI and loads to be fully controlled, with no disturbances. Its low gate current down to 10 mA helps optimize the power supply and allows direct drive capability through a single resistance between the microcontroller and Triac. 800 V T-series triacs are housed in TO-220AB, TO-220FPAB and now in D2PAK.



eDesignSuite is a comprehensive set of easy-to-use design-aid utilities ready to help you streamline the system development process with a wide range of ST products.

Power Management Design Center

Thermal-electrical Simulators for Components

Signal Conditioning Design Tool

NFC/RFID Calculators

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Power Supply Design Tool

SMPS design, by topology, by type and by product
PFC design with analog and digitial control
Supports various PCB configurations
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Solar Battery Charger

LED Lighting Design Tool

Handles AC-DC and DC-DC design in common topologies
Displays interactive and annotated schematic
Provides current/voltage graphs, Bode plots, efficiency curves and power-loss data
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Digital Power Workbench

Provides a step-by-step optimized design of power section and control loop
Generates the STM32Cube embedded software package for custom applications and allows firmware project generation, compatible with multiple STM32 IDEs

Power Tree Designer

Specify input/output power for each node in the tree
Check for consistency
Design each individual node
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AC Switches Simulator

Select ratings and application waveforms
Get junction temperature and blocking voltage graphs
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Rectifier Diodes Simulator

Select ratings and application waveforms
Estimate power losses
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Supports long mission profiles
Provides power loss and temperature graphs
Helps define heatsink thermal properties

Twister Sim

Help select the right ViPOWER Automotive power device
Supports load-compatibility, wiring harness optimization, fault condition impact and diagnostic analysis
Supports various PCB configurations

TVS Simulator

Specify system ratings and surge waveform
Search and sort suitable devices


Build simple schematics and firmware inputs in minutes
Quickly generate reliable estimates of battery life, system power consumption and bill of materials costs
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Active Filters

Handles multi-stage-designs and common topologies
Returns circuit component values
Provides gain, phase and group delay graphs
Low Pass, High Pass and Band Pass


Handles most common configurations
Returns circuit components values
Provides I/O signal waveforms
Inverting, Non Inverting, Window

Low side Current Sensing

Returns circuit component values
Provides current error graphs

High side Current Sensing

Provides current error graphs.
Help to select the right High side current sensing and shunt devices.
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NFC Inductance

Input geometry and substrate properties
Get antenna impedance

UHF Link Budget

Enter forward and reverse link characteristics
The tool returns link budget estimate

NFC Tuning Circuit

Enter antenna parameter and matching target
Select the topology of the matching network
The tool returns component values for the desired design targets