Littlefuse has added a new overvoltage protection series, the TwinChip SDP, to its broadband optimized SIDACtor product line. It provides bidirectional protection to limit DSL secondary line voltage to a safe 43 V peak level. And offers surge current ratings up to 100 A under lightning surge test conditions of 2x10 µs (repetitive waveform). This maintains the transformer-provided isolation, which typical rail clamps on the secondary side do not, said Littlefuse. Moreover, the TwinChip design results in a lower and more stable off-state capacitance than typical thyristor overvoltage protection, so there is less chance of signal waveform distortion, added the supplier.

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The growing use of ADSL2+ and VDSL2, particularly in Multi-Service Access Networks (MSANs), has heightened the industry's sensitivity to failures caused by lightning surges and other transient overvoltage events. The TwinChip SDP series provides a fast switching and robust solution that prevents surge events from being shunted into the ground and power plane.

According to Littlefuse, the new product line is UL recognized, (File #E133083), RoHS compliant, and has no inherent wear-out mechanisms when operated within its specified parameters. Since this product is installed across the secondary side of DSL coupling transformers ahead of the driver amplifier, it is not connected to the ground reference or the power rail, stated the manufacturer. As a result, it preserves the differential isolation provided by the transformer and represents an improvement over rail clamp diode arrangements that route surge currents into ground or power reference points, noted Littlefuse.

The TwinChip SDP series combines higher surge ratings with a smaller package size to meet OEM demands for higher component density and greater installation efficiency. Its compact QFN package has typical dimensions of 0.118" x 0.118" x 0.39", and comes ready for surface mounting on DSL line cards with a tape and reel assembly. The OEM reel quantity is 5000. OEM samples are available from stock, according to the supplier.

www.littlefuse.com