New unidirectional SIDAC switching thyristors for capacitor discharge applications

Two new product series, the Kxxx0S1URP and Kxxx0GURP Series unidirectional silicon diode for alternating current (SIDAC) switching thyristors have been introduced by Littelfuse. A SIDAC is a semiconductor switch used in conjunction with a capacitor and a transformer in capacitor discharge ignition (CDI) circuits for generating high-voltage spikes. The Kxxx0S1URP and Kxxx0GURP Series offer lower switching losses than existing high-energy SIDAC and standard SIDAC products. A new SIDAC design provides a higher repetitive pulse current (ITRM) rating at higher ambient temperatures, improved breakover / trigger voltage vs. temperature characteristics, and lower switching loss. This allows existing circuits to support higher voltage outputs, and ensures stable voltage outputs at high ambient temperatures. Typical applications for the Kxx0yU Series SIDAC/Unidirectional Thyristors include high-power flame ignition modules designed for gas cooking appliances ranging from portable, tabletop types to commercial-grade multiple-burner models, gas water heaters and oil heaters of all sizes, and ion generators. “In a typical high-power gas ignition circuit, the SIDAC acts like a switch to discharge energy from the capacitor rapidly,” said Daisy Wang, product marketing manager for the line. “The high instantaneous rate of current change (di/dt) of the pulse current from the discharge drives a high pulse voltage output on the secondary side of the transformer to create an ignition spark in the spark gap.”