Method to control current imbalance between differential pairs providing a dc power feed

Abstract

The present invention provides a method to at least partially power an Ethernet device from a plurality of balanced network power signals received through a network connection. This involves attaching the network device to the network, wherein network signals are received and contain both power signals and/or data signals. These network signals may be passed through surge protection and power-conditioning circuitry wherein the output of these circuits may be provided to a power absorbing circuit. This power absorbing circuit may separate the communication signal and power signal from the network signal. The communication signal may be passed to a network physical layer while the power signal may be passed to a power distribution module. Additionally, because certain embodiments may provide multiple pairs of network power signals to the power absorbing circuit, the current or power associated with each power signal must be sensed and balanced. This may be done with an active control circuit. The balanced power signals may then be supplied from the power absorbing circuit to the network-attached device in order to at least partially power the network-attached device.