Sensitive-gate thyristors with 8 A current rating for dimmer switch control

The TS820 silicon-controlled rectifier (SCR) thyristors from STMicroelectronics are ideal for use in dimming light switches for low-power LED or fluorescent lamps, providing flicker-free output and high power efficiency.

The TS820 series of SCR thyristors from STMicroelectronics provide an efficient way to control the current through lighting dimmer switches thanks to the highly sensitive gate. The low gate current means that the SCR thyristors can be controlled by a very small power supply.  


The 8 A-rated TS820 SCR series is suitable for all modes of control found in dimmer switches, and in other applications such as over-voltage crowbar protection, motor control circuits, inrush current limiting circuits, capacitive discharge ignition, and voltage regulation circuits. 


The SCR thyristors are available in through-hole and surface-mount packages.  


  • Triggering gate-current range: 0.2 mA to 15 mA 
  • Voltage-rating options: 600 V or 800 V 
  • Package options:  
    • DPAK 
    • IPAK 
    • TO-220AB 
    • TO-220FPAB 
  • Operating-temperature range: -40°C to 125°C 


  • Power tools  
  • Kitchen equipment  
  • Lighting equipment  

Evaluation Board

Part supported: TS820 

Board part number: STEVAL-ILD003V1 

The STEVAL-ILD003V1 demonstration board implements a low-cost analog dimmer using the TS820-600FP, a sensitive-gate silicon-controlled rectifier (SCR) thyristor. The dimmer can drive typical low-power lamps such as compact fluorescent or dimmable LED lights. 


Through-hole technology is used for the most important components, such as an LC filter, gate resistor, and turn-on delay capacitor, to allow for modification of the board. 


The STEVAL-ILD003V1 eliminates flickering thanks to its continuous current applied through the sensitive SCR gate. This dimmer could easily replace a standard low-cost analog triac light dimmer using a diac-controlled circuit. 


The STEVAL-ILD003V1 is for use in Europe at a mains voltage of 220 V. A 110 V version, the STEVAL-ILD003V2, is for use in North America.  


Key features: 

  • For 2-wire wall dimmers 
  • Leading-edge control compatible with all lamp types commonly found on the market 
  • Dimmable power range: 3 W to 350 W  
  • 60°C maximum ambient temperature  
  • Higher than 99% power efficiency at 350 W/230 V 
  • Less than 0.5 W standby power losses  


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