Polarity correction bridge controller for combined power over ethernet system

摘要

A system for combining power to a load in a Powered Device (PD) using Power Over Ethernet (PoE) receives power from a first channel and power from a second channel, via four pairs of wires. A MOSFET bridge for each channel is initially disabled. A bridge controller IC simultaneously senses all the voltages and controls the bridge MOSFETs. The bridge controller IC also contains a first PoE handshaking circuit. A second PoE handshaking circuit is external to the bridge controller IC and operates independently. The body diodes in the MOSFET bridge initially couple the first channel to the second PoE handshaking circuit while isolating the second channel. The second handshaking circuit then couples the first channel to the load. The first handshaking circuit then carries out a PoE handshaking routine for the second channel. Ultimately, the bridge controller controls the bridge MOSFETs to couple both channels to the load.

主权项

1. A system for combining power to a load in a Powered Device (PD) using Power Over Ethernet (PoE), the system receiving at least four pairs of wires from at least one Power Sourcing Equipment (PSE), the four pairs of wires comprising a first channel of two of the pairs of wires and a second channel of the other two pairs of wires, each pair of wires carrying a common mode voltage, the first channel supplying first voltages across the two pairs of wires, and the second channel supplying second voltages across the other two pairs of wires, the system comprising:
an active bridge comprising controllable bridge switches, a first set of the bridge switches being connected to the first channel for supplying the first voltages to the load, a second set of the bridge switches being connected to the second channel for supplying the second voltages to the load; a first controller circuit comprising an active bridge controller circuit and a first interface controller circuit, the active bridge controller circuit controlling conduction of the first set of bridge switches and the second set of bridge switches, the first interface controller circuit containing a first PoE handshaking circuit to ensure the PD is compatible with the at least one PSE; a second interface controller circuit, external to the first controller circuit, containing a second PoE handshaking circuit to ensure the PD is compatible with the at least one PSE; a series switch controlled by the second interface controller circuit for supplying the first voltages to the load when turned on after a successful PoE handshaking routine performed by the second PoE handshaking circuit; a detector in the first controller circuit configured to detect the supplying of the first voltages to the load; and a control circuit in the first controller circuit configured for carrying out the following routine:
a. controlling the first set of bridge switches to be on to supply the first voltages supplied by the first channel to the load only after it has been detected that the second interface controller circuit has turned on the series switch to supply the first voltages to the load; andb. after step a, performing a PoE handshaking routine by the first PoE handshaking circuit via the second channel with the at least one PSE and, upon a successful PoE handshaking routine performed by the first PoE handshaking circuit, controlling the second set of bridge switches to be on to supply the second voltages to the load, such that power from the first channel and power from the second channel are combined to provide power to the load.