High-Power Power over Ethernet (HPOE) standard has not yet been determined. Most people expect the standard is: supply voltage to 53 VDC, each of the available current of 750 mA, the cable is not more than 12.5 ohm impedance. If some people expect designed to 46 VDC (nominal 48 V) voltage, 720 mA current, 12.5-ohm impedance cable, it will be perhaps the worst situation. Because in the 720 mA, the cable will have a 9 VDC of the pressure drop, while the remaining can be used for the voltage of 37 VDC. This cable end of the output power of about 26.6 W, followed by a typical power circuit can only produce slightly more than 20 W of power. Unfortunately for many applications is, it is still not sufficient power. One solution is to use multiple Ethernet line, but it appears the distribution of power. The following example of the questions to answer laptop battery .
HPOE interface from the traditional one polarity protection rectifier bridge and a power supply Ethernet interface with the hot-swappable components HP PP2210 Series battery . HPOE after the interface is to provide a stable output isolation converters. The best situation is not dependent on the export of these loads, and they are all good transient response. It seems that those at the time have contributed to the typical design used to produce isolated feedback voltage (typical value of 5.0 VDC), the voltage and then converted to the other voltages. Often, multiple output trying to share a feedback loop, but if so regulators will be more dependent on the load. In either case, the bridge rectifiers and converters, the loss will bring very poor efficiency. Moreover, the feedback loop isolation and will have a very poor transient response. Unfortunately, on HPOE, its overall point is not to sacrifice performance under the premise of as little as possible from the Ethernet network more useful online access to power.
Examples on the HPOE interface and power converters, we can obtain from the two additional percentage of efficiency, and provide excellent transient response. Figure 1 gives a 47 W output dual Ethernet line on the design of one of two HPOE interface. Two N-channel and two P-channel MOSFETs each have a minimum loss of the bridge rectifier. Each MOSFET by a line from the opposite polarity enter the 150 K-on-resistance bias (ON) status. Gate by the low current Zener diode (equivalent to test current 50 uA) protection. Only with the correct polarity of the two MOSFETs will be conducting. MOSFETs of the leak – as a bridge rectifier diode source until 150 K resistance to the gate of the MOSFETs charge. HPOE interface integrated circuits help to simplify and provide all the necessary interface and hot-swap functions.