BOURNS TVS Thyristor, Diac, 240V, DO-214AA (SMB), 2 Pin

The BOURNS TISP4240M3BJR-S is a bidirectional thyristor surge protector, specifically engineered as an overvoltage protector series for safeguarding telecommunications lines. Its primary function is to limit dangerous overvoltage spikes on telephone lines, which are commonly induced by AC power system disturbances or lightning strikes.

This single, compact device provides effective 2-point protection, making it a typical solution for protecting 2-wire telecommunication equipment such as telephones and modems. It is installed between the ring and tip wires to shunt harmful surges. For more complex systems, multiple devices can be combined to create multi-point protection networks, for example, offering 3-point protection between ring, tip, and ground lines.

Core Technology and Operation

The protector utilises a symmetrical, voltage-triggered bidirectional thyristor. When an overvoltage occurs, the device initially clamps the spike through breakdown clamping. If the voltage continues to rise to the breakover level, the device 'crowbars' into a low-voltage on state. This action safely diverts the surge current through the thyristor, protecting the connected equipment. A high crowbar holding current is a key feature, helping to prevent DC latchup as the diverted current subsides, ensuring the device resets correctly.

Key Features and Benefits

• Ion-Implanted Breakdown Region: Provides precise and stable voltage characteristics for reliable triggering.
• Precise and Stable Voltage: Ensures consistent protection thresholds.
• Low Voltage Overshoots Under Surge: Minimises the voltage let-through during a transient event, offering superior equipment protection.
• Robust Construction: Housed in a compact DO-214AA (SMB) package, it is designed for industrial applications and demanding environments.

This thyristor is an essential component for engineers designing or