Circuit Protection of xDSL/Dial-Up
Design Notes:
Protection Application:
The signals carried on the tip and ring lines by dial-up and xDSL circuits operate in a range from voice frequency through 60 Mbps. For dial-up circuits, the capacitance of the protection device is not important. However, for high frequency versions of DSL, the capacitance of the suppressor needs to be taken into account to ensure signal integrity. The electrical threats include lightning surges and Power Cross conditions.
Solution Description:
As shown at the left (top), a fuse or PTC can be used for Power Cross protection, and a SIDACtor thyristor for lightning surge protection. In circuits where capacitance needs to be minimized, a gas discharge tube (left bottom) replaces the SIDACtor for surge protection. The specific part numbers are determined by matching the operating voltage, and surge’s peak pulse current value to that of the surge suppressor.
Companion Solutions:
Does not apply.
Regulatory Issues:
In customer premises equipment like set top boxes, there are a number of safety and performance-based Regulatory standards that apply. These include: TIA-968 GR-1089 ITU K.20, K.21 UL 60950/EN 60950
Unique Features:
Does not apply.
Application Warnings:
Does not apply.

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