PD in PoE system having redundant PSE channel inputs

摘要

A Powered Device (PD) in a PoE system has two input channels, each being coupled to a separate Power Sourcing Equipment (PSE) for increased reliability. A first PD controller is coupled to the first channel to perform hand-shaking and closes a first Power Good (PWRGD) switch when the PoE voltage is detected on the first channel. A second PD controller is coupled to the second channel to perform hand-shaking and closes a second PWRGD switch when the PoE voltage is detected on the second channel. A diode bridge couples both channels to a single regulating power supply that supplies power to a load. Auxiliary switches are controlled by the PWRGD signals so that only the first channel or the second channel is coupled to the diode bridge in the event that both channels receive the respective PoE voltages. Therefore, hot standby is provided using only one power supply.

主权项

1. A Power Over Ethernet (PoE) system, the PoE system being configured to deliver operating power to a load in a Powered Device (PD) via data lines, the PoE system comprising:
a Powered Device (PD) having a first channel and a second channel, the first channel comprising a first wire pair, the second channel comprising a second wire pair, the PD further comprising:
a first PD controller having input terminals coupled to the first wire pair, the first PD controller being configured to perform hand-shaking with a first Power Sourcing Equipment (PSE) coupled to the first channel to identify to the first PSE that a first PoE voltage is to be provided on the first channel, the first PD controller having a first Power Good (PWRGD) terminal for issuing a first PWRGD signal upon the first PoE voltage being detected on the first channel;a second PD controller having input terminals coupled to the second wire pair, the second PD controller being configured to perform hand-shaking with a second PSE coupled to the second channel to identify to the second PSE that a second PoE voltage is to be provided on the second channel, the second PD controller having a second PWRGD terminal for issuing a second PWRGD signal upon the second PoE voltage being detected on the second channel;a first PWRGD switch controlled by the first PD controller, the first PWRGD switch being connected in series with a first wire in the first wire pair, the first PWRGD switch being controlled to be closed upon the first PD controller issuing the first PWRGD signal;a second PWRGD switch controlled by the second PD controller, the second PWRGD switch being connected in series with a second wire in the second wire pair, the second PWRGD switch being controlled to be closed upon the second PD controller issuing the second PWRGD signal;a rectifying bridge coupled between the first PD controller and a regulating power supply, and coupled between the second PD controller and the regulating power supply;a first current load in the first channel drawing at least a minimum current needed to cause the first PSE to continue to supply the first PoE voltage to the first channel when the first PWRGD switch is closed and when the load is not drawing a current from the first channel;a first auxiliary switch connected in series with the first PWRGD switch between the first PD controller and the rectifying bridge; anda second auxiliary switch connected in series with the second PWRGD switch between the second PD controller and the rectifying bridge,the first auxiliary switch and the second auxiliary switch being controlled by the first PWRGD signal and the second PWRGD signal to be in opposite states when one or both of the first PWRGD signal and the second PWRGD signal are issued,the first auxiliary switch and the second auxiliary switch being controlled by the first PWRGD signal and the second PWRGD signal to be both open when neither the first PWRGD signal nor the second PWRGD signal is issued,wherein only one of the first channel or the second channel is coupled to the rectifying bridge when the first PSE is supplying the first PoE voltage and the second PSE is supplying the second PoE voltage.