Telecom Transformers

Telecom transformers are used in applications which require high bandwidths and fast switching speeds. They isolate the signal between primary and secondary grounds. There are many types of telecom transformers. Examples include DSL transformers, xDSL transformers, T1 transformers, E1 transformers, ISDN transformers, LAN transformers, WAN transformers, and ATM transformers. Modem transformers are also available. A DSL transformer or xDSL transformer uses the digital subscriber loop (DSL) or extended digital subscriber loop (xDSL) telecommunication protocols. A T1 transformer or E1 transformer is designed for use with a T1 line or an E1 line, respectively. An ISDN transformer is a telecommunications transformer for integrated services digital network (ISDN), an international standard for the digital transmission of voice and data. A LAN transformer is designed for a local area network (LAN), while a WAN transformer is used with a wide area network (WAN). An ATM transformer works with asynchronous transfer mode (ATM), a packet switching and transmission system also known as cell relay. Like other telecommunications transformers, a modem transformer needs to minimize noise. 

Performance specifications for telecom transformers include operating frequency range, direct current resistance (DCR), insertion loss, isolation or high potential (hipot) level, three-decibel (dB) bandwidth, operating temperature, and maximum dimension. Direct current resistance (DCR) is the resistance of the telecom transformer’s winding as measured with DC current. It is usually specified as a maximum rating. Insertion loss is defined as the measured loss through the device excluding the power division factor. It is measured in decibels and calculated as the ratio of power output to power input. Isolation or hipot level is the maximum voltage that can be applied to a telecom transformer without breaking the winding or dielectric. Three-decibel or 3 dB bandwidth is the frequency range over which the insertion loss for telecom transformers is less than 3 dB referenced to the mid-band insertion loss. 

Telecom transformers differ in terms of package type and packing method. Integrated circuit (IC) package types include flat pack (FPAK), single in-line package (SIP), dual in-line package, and small outline integrated circuit (SOIC). Board-level telecom transformers can use either surface mounted technology (SMT) or through hole technology (THT). SMT adds components to a printed circuit board (PCB) by soldering component leads to the top surface of the board. Through hole technology (THT) mounts components by inserting leads through holes and then soldering the leads in place on the opposite side of the board. Waveguide assemblies and connectorized telecommunications transformers are also available. In terms of packing methods, telecom transformers can be packed in trays, tubes, or tape reel assemblies. Bulk-pack products are distributed as individual parts. 

Telecom transformers are certified and approved by organizations such as the American National Standards Institute (ANSI), the Canadian Standards Association (CSA), the International Electrotechnical Commission (IEC), Underwriters Laboratories (UL), TÜV Rheinland/Berlin-Brandenburg (TUV), and Verband Deutscher Elektrotechniker (VDE). Gate drive transformers that are sold in European Union (EU) nations must comply with the Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronics Equipment (WEEE) directives.