Designing Protective Circuitry For Dsl Loops: Beware Of Pitfalls

摘要

The appropriate protective-circuit design for DSL (digital-subscriber-line) loops depends on the type of loop: Loops vary in voltage conditions and in susceptibility to attenuation and degrada-tion in signal integrity. Therefore, protective cir-cuitry that works well in one application may be completely inappropriate in another. A "normal" signal ranges from 2.5V in an HDSL (high-bit-rate DSL) to 260V in an DSL system (see sidebar "Normal signals"). The circuit design and choice of circuit-protection devices must take these differences into account. You should also consider the design with respect to effects of varying capacitance.