TP-DCDC-1248D is the  DC to DC converters offered by Tycon Power Systems are a 
low cost and high reliability solution for those requiring 48VDC 802.3af Power 
Over Ethernet voltage from a 12 or 24V battery system. 
They have an integrated 802.3af PoE injector to apply the regulated 48VDC to 
the CAT5 Ethernet cable. The input voltage must be between 9VDC and 36VDC. 
They accept data-in to a shielded RJ45 Jack and provide data-out and PoE 
power on the shielded RJ45 output jack. They work by supplying power on the 
unused Ethernet pins 4,5(V+) and 7,8(V-). 
They have various protections for surge, short circuit and overload. The 
units have power output of 17W.