Embodiments of the present invention provide an integrated circuit (IC) having an integrated DC-DC power converter therein. This IC is operable to support the distribution of combined power and data signals in a network environment such as an Ethernet network according to protocols such as the power over Ethernet (PoE) protocol. The IC includes a DC-DC power converter, a power feed circuit, and a network physical layer (PHY) module, wherein the PHY module may contain fine line structures susceptible to damage when exposed to excessive voltages. To prevent or reduce the likelihood of damage to the PHY module from voltages supplied to the DC-DC power converter, a common substrate ground is shared between the IC components.