Design of Current Equalization Circuit in Dual Ethernet Power Supply System

Abstract

A current-balancing circuit for a dual-channel Ethernet power supply system is designed in this paper, which can be used to solve the mismatch between the two channels caused by unavoidable factors, such as mismatched resistances, temperatures and voltages. Based on the design, the mismatch of the currents between the two power transmission paths can be controlled to be less than 1% of the original ones. It can be operated under these conditions with the changes of the load current and the PSE output voltage. The maximum output power of the dual-channel power supply can reach up to 96.5 W. When the DC–DC conversion efficiency is less than 75%, it can still provide 72 W for the PD end, meeting the requirements of the PoE power system. The current-balancing circuit designed in the paper has potential application value to improve the dual PoE power supply system.

Keywords

• Power over Ethernet (PoE)
• current balancing
• MOSFET rectifier bridge
• power supply sensitivity
• temperature sensitivity