STMicroelectronics DIAC / SIDAC Trigger Diode, 28V to 36V, 50µA, SOT-23

The STMicroelectronics SMDB3 DIAC/SIDAC is a 32V VBO (Voltage Breakover) trigger diode, designed to provide a precise and fixed voltage reference for switching applications. This surface-mount component simplifies control circuits, particularly when used in conjunction with TRIACs for AC power control, by offering a reliable trigger mechanism that activates at a predetermined voltage threshold.

A key advantage of this device is its extremely low breakover current of just 50µA, ensuring efficient and sensitive triggering. This makes it an ideal starting element in electronic ballasts for fluorescent lighting, where precise control is essential for reliable lamp ignition and stable operation. Its compact SOT-23 package allows for high-density PCB mounting, saving valuable board space in modern electronic designs.

Primary Applications & Features

• Simplified Gate Control: Functions as a trigger diode for TRIACs, enabling straightforward design of AC phase-control circuits for lighting dimmers, motor speed controllers, and heater regulators.
• Lighting Ballasts: Serves as a robust and reliable starting element in electronic ballasts for fluorescent lamps, ensuring consistent performance.
• Power Management: Suitable for various power management and protection circuits requiring a precise voltage-triggering element.
• Surface-Mount Design: The SOT-23 package is designed for automated assembly processes, offering excellent reliability and a small footprint.

With a wide operating temperature range of up to 125°C, this DIAC is built to perform reliably in demanding environments. The combination of a tightly specified breakover voltage range (28V to 36V) and minimal current requirement provides designers with a predictable and stable component for critical triggering functions in both consumer and industrial electronics.