Reference Designs

This section offers specific examples of how Littelfuse circuit protection devices can be used to ensure longterm operability of protected equipment and uninterrupted service during overcurrent and transient electrical activity.

For assistance on new designs not covered below, contact a littelfuse technical support for assistance.

Files

Application Notes
	Analog Line Cards  Given that line cards are highly susceptible to transient voltages, network hazards such as lightning and power cross conditions pose a serious threat to equipment deployed at the central office and in remote switching locations. To minimize this threat, adequate levels of protection must be incorporated to ensure reliable operation and regulatory compliance. 3Analog.pdf (196 K)
	CATV Equipment Protection  As cable providers enter the local exchange market, protection of CATV (Community Antenna TV) equipment becomes even more critical in order to ensure reliable operation of equipment and uninterrupted service. 5CATV.pdf (109 K)
	Customer Premises Equipment (CPE)  CPE is defined as any telephone terminal equipment which resides at the customer's site and is connected to the Public Switched Telephone Network (PSTN). Telephones, modems, caller ID adjunct boxes, PBXs, and answering machines are all considered CPE. 1CPE.pdf (119 K)
	Data Line Protectors  In many office and industrial locations, data lines (such as RS-232 and ethernet) and AC power lines run in close proximity to each other, which often results in voltage spikes being induced onto the data line, causing damage to sensitive equipment. 9DataLine.pdf (94 K)
	High Speed Transmission Equipment  High speed transmission equipment encompasses a broad range of transmission protocols such as T1/E1, xDSL, and ISDN. Transmission equipment is located at the central office, customer premises, and remote locations. 2HighSpeed.pdf (147 K)
	LAN / WAN Protectors  10LANWAN.pdf (101 K)
	PBX Systems  PBXs, KSUs, and PABXs contain line cards that support various transmission protocols such as ISDN, T1/E1, HDSL, and ADSL. PBXs also have features such as a POTS (plain old telephone service) pull-through which allows stations to have outside line access in the event of power failure. All incoming lines to the PBX are subject to environmental hazards such as lightning and power cross. 4PBX.pdf (124 K)
	Primary Telecom Protection  Primary telecommunications protectors must be deployed at points where exposed twisted pairs enter an office building or residence. This requirement is mandated in North America by the National Electric Code (NEC) to protect end users from the hazards associated with lightning and power cross conditions. 6Primary.pdf (110 K)
	Secondary Telecom Protection  Secondary protectors (stand alone units or integrated into strip protectors and UPSs) are adjunct devices used to enhance the protection level of customer premise equipment (CPE). Due to the inadequate level of protection designed into CPE, secondary protectors often are required to prevent premature failure of equipment exposed to environmental hazards. 7Secondary.pdf (129 K)
	T1/E1/J1 Asymmetrical Protection  t1e1prot.pdf (67 K)
	T3 Protection  t3prot.pdf (52 K)
	Triac Protection  Damage can occur to a thyristor if the thyristor's repetitive peak off-state voltage is exceeded. A thyristor's repetitive peak off-state voltage may be exceeded due to dirty AC power mains, inductive spikes, motor latch up, and so on. 8Triac.pdf (99 K)