By John Colwell
 300 Series modular jacks from Corcom Inc. |
In the passive components and interconnection arena, connector manufacturers are integrating magnetics, filters and resistors within the modular jack housing.
Because of the explosive growth of connectivity in the modern enterprise, available space in wiring closets and data centers is at an all-time premium. Correspondingly, data communications devices, such as local area network (LAN) hubs, are migrating toward increasingly smaller footprints.
The trend toward smaller, more highly optimized communications devices has led component manufacturers to build smaller parts that combine several components within a single housing. An excellent example of this trend is the modular jack with integrated magnetics. In the active components arena, system-on-a-chip (SOC) designs are replacing multi-chip designs in next-generation equipment. In the passive components and interconnection arena, connector manufacturers are integrating magnetics, filters and resistors within the modular jack housing.
Integration Benefits
The most obvious advantage of integrating common mode filters, isolation transformers and/or electrostatic discharge (ESD) protection within the jack housing is a significant savings in board space. Bishop & Associates Inc. estimates that the potential savings in board space is between 1.62 and 1.75 sq. in. per port. This amounts to 26.0 sq. in. on a 16-port card.
 Figure 1. Shortened signal path between the transceiver chip and the modular jack improves performance. |
Moreover, integrating the magnetics within the jack housing allows designers to place the transceiver chip closer to the jack, which results in a shorter signal path, lower electromagnetic interference (EMI) susceptibility and better bandwidth performance (see Figure 1). For example, moving the components from the printed circuit board (PCB) and enclosing them within the connector housing, which can be enclosed within its own shield, can achieve significant reduction in noise.
Other advantages include fewer purchased components, fewer board placements and, most importantly, increased reliability. From a component count perspective, a single eight-port module with integrated magnetics replaces dozens of individual parts and their associated placement costs. From a reliability perspective, PCB-mounted magnetics are susceptible to temperature, shock and vibration, and are considered to be among the least reliable components of a system.
Protecting the Magnetics
Moving magnetic and other components off the PCB and into the modular jack housing improves the reliability of both the magnetic components and the overall system. However, connector manufacturers have done more than simply move the magnetics into the connector. FCI Electronics, for example, encloses the magnetics in protective housing that supports the coil, aligns and supports the lead wires, and protects the internal connections, which results in a highly integrated and reliable package. Stewart Connector Systems Inc. (Glen Rock, Pa.) and Corcom Inc. (Libertyville, Ill.) offer similar integrated designs that likewise improve reliability over PCB-mounted magnetics. Protecting the magnetics within the connector housing ensures that the overall device continues to operate cleanly and optimally.
 Figure 2. World market forecast for modular jacks with integrated magnetics. |
Having been available for approximately three years, the cost-effectiveness and reliability of integrated magnetics have been demonstrated with the result that board designers are increasingly incorporating them into their new designs. On a hard cost basis, the integrated product is approaching parity with the separate jack and PCB-mounted magnetics. However, on a total cost basis, the integrated magnetics approach offers very compelling advantages, including:
- Reduced board space
- Simplified design
- Fewer components to be purchased
- Fewer board placements
- Improved noise performance
- Improved signal bandwidth
- Higher reliability
Bishop & Associates Inc. estimates that the current world market for modular jacks with integrated magnetics is $40.2 million. By 2003, the forecast value of shipments is $135 million, representing a compound growth rate of 50 percent (see Figure 2).
JOHN COLWELL is director of market research, Bishop & Associates Inc., Telecom Market Group, 1209 Fox Glen Drive, St. Charles, IL 60174; (630) 443-2702; Fax: (630) 443-2704; Web site: www.connectorindustry.com.
