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PP0640SA - PP3500SC

APPliCATion inFoRmATion

FiguRe 3 - ul 1459 & FCC PART 68 meTAlliC & longiTuDinAl PRoTeCTion

Three equal TSS devices are used in this application for metallic (tip-to-ring) and longitudinal (tip-to-ground and ring-to-ground) protection. For analog signals, the

PP3100SB/SC is recommended. With a resistance value of 15 Ohms for the tip and ring resistors, the PP3100SA may be used. The National Electric Code (NEC) article

800 requires two fuse elements when connecting to ground. Fuses or a suitable Positive Temperature Coefficient (PTC) automatic resettable current limiting device

may be used. This circuit is recommended for protection against the Bellcore requirement: First Level Lightning Surge Tests (Telecommunications Port), document #

GR-1089-CORE.

To Protected

Equipment

TIP

RING

R

Tip

R

Ring

CiRCuiT boARD ReCommenDATionS

Circuit board layout is critical for electromagnetic compatibility protection. The following guidelines are recommended:

• The protection device should be placed near the input terminals or connectors, the device will divert the transient current

immediately before it can be coupled into the nearby traces.

• The path length between the TVS device and the protected line should be minimized.

• All conductive loops including power and ground loops should be minimized.

• The transient current return path to ground should be kept as short as possible to reduce parasitic inductance.

• Ground planes should be used whenever possible. For multilayer PCBs, use ground vias.