Главная Оборудование Программное обеспечение Поддержка О фирме Контакты

Passive POE adapter POE1A2

POE Passive Power over Ethernet injector

  • Status: active
  • Part numbers: poe1a2 = POE adapter, RoHS compliant
  • Spec: Passive POE (Power Over Ethernet) adapter, uses unused pairs of 100baseT network cable to transmit power to remote device.
  • Pinout: DC jack center positive, 2.1 mm pin. RJ45 pins 4,5 = positive, RJ45 pins 7,8 = negative.
  • Issues:
    - Passive POE does not comply with the IEEE 802.3af specification.
    - To minimize cable losses, feed the highest allowed voltage, e.g. 18V. Demarc Technology has a nice POE voltage drop calculator - select 1 pair for correct results. Keep in mind that WRAP input power is fairly constant over input voltage - when the input voltage drops, the current goes up. Power = voltage * current.
    -To avoid ground loops, ground should be referenced on the receiving end only, that is use a 2 prong (non grounded) AC adapter.
  • Why not active POE?
    - Cost - 802.3af compliant solutions require a high component count, and compliant switches are too expensive for small installations such as CPE.
    -Board space - DC-DC isolation transformer takes a lot of space.
    -Efficiency - DC-DC converter is required for 802.3af. Typical solution is a flyback inverter, maybe 70% efficiency. Unless you have a very long cable run, passive POE will be more efficient overall.
  • Manufacturer: PC Engines
  • Origin: Taiwan


Rambler's Top100 Рейтинг интернет-магазинов hotline.ua Консалтинговые услуги