Japan develops two-way thyristor to deal with LED all-out failure

Japan's Shinden Electric Industrial Co., Ltd. has developed a two-way thyristor "K1VZL09/K1VZL20" that can prevent all lights from being extinguished in the event of an LED open circuit failure, and will be mass-produced in April 2010. It is mainly used for street lights, emergency lights, light projectors, and signal lights that cannot be extinguished. The product name is "SAIDAC".

In a lighting fixture composed of a series LED, when one LED has an open circuit failure, all the LEDs connected thereto are extinguished. Moreover, due to the effects of a malfunctioning LED, the voltage may rise and destroy other LEDs. Therefore, it has been solved by the method of connecting Zener Diode with LED. However, this method has a problem in that since a reverse voltage Zener diode higher than the LED driving voltage is required, the amount of heat generated when the Zener diode is in the bypass state is very large.

The product developed to solve the above problems is the bidirectional thyristor of this time. A bidirectional thyristor is a semiconductor component in which a load voltage exceeds a breakdown (turning) voltage and is turned into an on state. Moreover, the forward loss of the triac is small, "only about 1/5 of the Zener diode" (new electric power industry). Therefore, the amount of heat generated in the bypass state can be drastically reduced.

The difference between K1VZL09 and K1VZL20 is the breakdown voltage. K1VZL09 is intended for the use of 1 to 2 standard +10V voltage LEDs in series. The K2VZL20 is intended for use in series with 3 to 5 standard +20V voltage LEDs. The on-state current is up to 1A and the off current is up to 5μA. The holding current is up to 20mA. The temperature of the joint ranges from -40 to +125 °C. The external dimensions are 5mm × 2.5mm × 2mm. Sample shipments are now available. The sample price is 80 yen. (Editor: maysoong)

Bidirectional thyristor for LED lighting failure countermeasures

Current and voltage characteristics of the triac. Measurement using a diode tracer (Curve Tracer)

The scenario when a triac is actually used. Even if one LED has an open-circuit fault, the tri-directional thyristor power can be turned into a bypass, so the other LEDs in series will still light up normally.