What is a Silicon Transient Voltage Suppressor and how does it work?

Silicon transient voltage suppressors (TVSs) are clamping devices that limit voltage spikes by low impedance avalanche breakdown of a rugged silicon pn junction. They are used to protect sensitive components from electrical overstress such as that caused by induced lightning, inductive load switching and electrostatic discharge.

When a transient appears the TVS becomes active, clamping it to a harmless level. Its electrical parameters such as breakdown voltage (V(BR)), leakage current (ID), and capacitance should be "invisible" to the circuit and have no effect on performance.

The reverse standoff voltage (VWM), which approximates the circuit operating voltage is normally 10% below breakdown voltage. This assures minimal standby leakage current and compensates for voltage excursions caused by temperature variations. The TVS clamps instantly when transients occur, limiting the spike voltage to a safe level while diverting damaging currents away from the protected part. These functions are illustrated in Figure 1 .