On 26 April 2012 15:34, Harold Hallikainen wrote: > I've got a product with a PIC32 in it that I'm currently driving with a > 250mA 5V USB style power supply. I'm using a simple linear regulator to > drop it to 3.3V for the digital, while keeping the 5V for the analog. > > Customers don't want to run two wires (Ethernet and USB Power). So, > there's always Power Over Ethernet. But, it looks complicated and > expensive, especially for the 2 watts or so we need (a lot more than we'r= e > currently spending for the USB power supply, cable, connectors, and linea= r > regulator). > > But, it seems like this should be a common problem with a low cost modula= r > solution. Linear and TI and others are making switching DC to DC converte= r > modules, some of which are pretty inexpensive. It SEEMS like there should > be such a module for POE. It'd have the two diode bridges, load switch, D= C > to DC converter, and a DC output. But, I can't find anything like that > (well, I did find one for $35). Most of the POE stuff is emphasizing high > power (and cost). > > Does anyone know of a low cost POE PD module? > > THANKS! > > Harold Harold IIRC RJ45 connected ethernet - at least for PICs - use transformer coupling at both ends and typically use only 2 of the 4 available pairs. So it should be possible to arrange a power feed by either using the "spare" pairs in the RJ45 connection, or to arrange centre tapped transformers to feed the power & return down the 2 used pairs. Just so long as the voltage and power levels are low. And whtch out for high surge currents when connecting and capacitors charge up. Can't much more simple than that - or am I missing something? RP --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .