A network interface comprises a medium access control (MAC) device and/or a host interface. A regulator module communicates with the MAC device and/or the host interface and provides a first voltage level during an inactive mode and a second voltage level during an active mode. A physical layer (PHY) device that communicates with the MAC device and/or the host interface and the regulator module and that includes an energy detect module that detects energy on a medium during the inactive mode and an energy save module. The energy save module starts timing a first period and the regulator module transitions the MAC device and/or the host interface to the second voltage level when the energy is detected during the inactive mode. External communication with the MAC device and/or the host interface is enabled after the first period is up.