Transient surge voltage suppressors and their performance in circuit over-voltage protection

Semiconductor components from electrical circuits and systems have a maximum permissible working voltage, specified for reliable operation. Short duration over-voltage of amplitude higher than this specified voltage can lead to system failure. Typical electrical characteristics for special components like varistors or silicon transient voltage suppressors, used in the circuit over-voltage protection are shown and analyzed. The advantages and disadvantages are outlined. The varistor type surge voltage suppressors are lower cost devices but with poor protection efficiency. Their operation temperature is limited to 85degC. The silicon avalanche breakdown based devices and thyristor based devices manifest good protection efficiency but at higher cost. Their operation temperature is higher than 100degC. At this time, commercial surge suppressors for efficient over-voltage protection below 5-6 V are not available.