Thyristor Power-Control Devices from Littelfuse Expand Usable Range of LED Lighting

Littelfuse, Inc. has introduced the Q6008LH1LED and Q6012LH1LED Series of Alternistor Triac and Q6008LTH1LED and Q6012LTH1LED Series of QUADRAC Thyristor Power Control Devices. These devices are designed for use as the switch in a dimmer circuit to adjust the light output of Light Emitting Diode (LED) bulbs and strings. They allow designers of ac-line based dimmers for LED lighting to accommodate a wide range of operating parameters without sacrificing reliability and without degrading the performance of the dimmer. As a result, a single control device can be used for LED-based dimmers or for combination dimmers designed for incandescent, compact fluorescent lamp (CFL), and LED loads.

“For the designers of environmental or theme lighting, the introduction of LED lighting has created some significant technical challenges. For example, these new lamps and strings have extremely low current draw, which causes traditional thyristors to turn off early, making it impossible to access one range of the lighting spectrum,” said Corey Deyalsingh, Product Director of the Littelfuse Thyristor Power Control Devices product line. “The low load current capability of these new thyristors makes it possible to create a single dimmer design that will cover all dimmable lighting loads: LEDs, CFLs, and traditional incandescents. The high rate of rise of current through these thyristors (di/dt) during turn-on and high junction temperature rating ensure greater reliability and design flexibility. Our new Q6008LTH1LED and Q6012LTH1LED Series QUADRAC devices further simplify circuit design and assembly by combining a diac and a triac in a single package.”

The Alternistor Triacs (Q6008LH1LED and Q6012LH1LED Series) and QUADRACs (Q6008LTH1LED and Q6012LTH1LED Series) Thyristor Power Control Devices offer these key features: Maximum holding current as low as 6mA; UL recognized TO-220AB package; 110°C rated junction temperature; Static dv/dt performance of 35V/µs; di/dt performance of 70A/µs; QUADRAC version includes integrated DIAC; And gated Triacs have 10mA gate sensitivity.

System benefits of using these devices include: Full control of light output at the extreme low end of load conditions; 2500Vac min isolation between mounting tab and active terminals; Improves margin of safe operation with less heat sinking required; Provides enhanced immunity from electrical noise; Enables survivability of typical LED load operating characteristics; Simplicity of circuit design and layout; And 600 Volts blocking capability.

Littelfuse Q6008LH1LED and Q6012LH1LED Series Alternistor Triacs and Q6008LTH1LED and Q6012LTH1LED Series QUADRACs are available in quantities of 500 in bulk and in tube packaging.