I am designing a device that will have Gigabit Ethernet ports on it. We have a requirement that our device must be stored at -50C. Many gigabit ethernet transformers either don't list a min storage temperature in the datasheet, or the min is -40C.
I found some non-PoE type gigabit ethernet transformers that supported storage temperatures down to -50C, but they were sort of expensive. One example being the Pulse HX5008FNL (like $6~$7 at quantity = 100).
https://www.mouser.com/datasheet/2/336/-595196.pdf
I also found some PoE type gigabit Ethernet transformers that supported storage down to -50C, and they were much cheaper. One example being the Bourns SM51625EL (like $1.50 at quantity = 100).
https://www.mouser.com/datasheet/2/54/sm51625el-934089.pdf
From the datasheets, both parts seem to have similar common mode rejection, insertion loss, cross talk, etc.
My device will not be implementing PoE, just regular gigabit data transfer, and I wont have the power supply controller that normally goes with a PoE transformer. But I want to use the cheaper part...
I know you can't use a non-PoE transformer for PoE, since they are not designed to handle larger currents. But is there any downside to using a PoE type transformer in a non-PoE application.
Also, I am using the VSC8541-2 Ethernet PHY. Page 25 of the datasheet shows that (if I wanted to) the chip can be used in PoE applications (with a separate PoE power supply).
https://ww1.microchip.com/downloads/en/DeviceDoc/VMDS-10513_VSC8541-02_VSC8541-05_Datasheet.pdf
