Power Electronics

Single-port PoE Injector Targets Gigabit Systems

Phihong’s PSA20U is a single-port power injector for Power-over-Ethernet (PoE) applications for use with gigabit systems. Unlike existing power injectors, the PSA20U is not limited to working only on 10baseT or 100baseT systems, but is compatible with systems up to 1000 Mbits/s.

Other available PoE injectors connect the power onto the spare conductors, disconnecting the connections from the incoming cable and applying the power to those conductors. While this works for 10baseT and 100baseT systems, the conductors in the 1000baseT system are not spare, but are used for data.

“Phihong’s PSA20U meets this challenge by connecting the power onto the data lines,” said Keith Hopwood, vice president of marketing for Phihong USA. “The single port injector does this successfully without corrupting the signal or causing any attenuation loss through the injector.”

According to Hopwood, network switch manufacturers have been doing this for awhile, but they have the advantage of data “phys” and special PoE transformers that act like repeater amplifiers to resolve any attenuation or insertion loss. Phihong has developed a way to do this without adding significant insertion loss. “The benefit is our products can be purchased and inserted anywhere—10baseT, 100baseT and now 1000baseT,” said Hopwood.

Another advantage of the 20U is that the output is designed to give 19.6 W while complying with IEEE 802.3af detection and fault protection requirements. Development of the gigabit single-port injector was driven by the high data-rate requirements of broadband wireless 802.11 access points and high-quality IP cameras with streaming video. These applications also require high power capabilities, easily met by the power injector’s 19.6-W output capability. Typical pricing for Phihong’s gigabit single port injector is $18 each in OEM quantities.

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