No Such thing as Ethernet with magnetics and POE SMD - Page 1
Forum section: electronics / projects

author: johnnyfp
author_rank: Frequent Contributor
timestamp: March 14, 2014, 08:41:32 pm
content: Have anyone come across an Ethernet Jack with Magnetics that has POE and is SMD (With or without LED)? The only one that I've found is frombelfuse.combut they have no stock. All the rest are through hole.thanks

author: marshallh
author_rank: Unknown
timestamp: March 14, 2014, 10:05:42 pm
content: Can't find any. Looks like you either have to buy in volume or go to PTH...

author: dumle29
author_rank: Regular Contributor
timestamp: March 14, 2014, 10:17:49 pm
content: Is it an actual rating for a plug to have POE? As far as I've understood it just drops the speed to base10/100 and then uses the remaining 4 pins for 40~50v DC (and some coms over the DC lines I think)

author: gxti
author_rank: Frequent Contributor
timestamp: March 14, 2014, 11:03:47 pm
content: Non-PoE magjacks don't bring out the unused pins, they're just tied to earth internally through a resistor. To bring them out would require more than 8 pins due to the center tap being brought out for the tx/rx, so they don't.People get picky about micro-USB jacks that are fully SMD, I can't imagine a bigass 8p8c connector would do well. Maybe there's a good reason they're hard to find?

author: David_AVD
author_rank: Super Contributor
timestamp: March 14, 2014, 11:08:22 pm
content: Agreed. Some connectors types are just not suited for SMD variants.

author: johnnyfp
author_rank: Frequent Contributor
timestamp: March 15, 2014, 12:28:26 am
content: But why would you get a Through hole MagJack with POE but not the Equivalent SMD variant. Specially today where it's all PnP and SMD. Just seems odd that there isn't one.

author: David_AVD
author_rank: Super Contributor
timestamp: March 15, 2014, 12:30:41 am
content: Mechanical strength (mounting to PCB) maybe?

author: johnnyfp
author_rank: Frequent Contributor
timestamp: March 15, 2014, 12:33:09 am
content: I can't see why. There are plenty of SMD non - POE Mag type connectors, How does bringing out 2 extra lines cause an issue.

author: gxti
author_rank: Frequent Contributor
timestamp: March 15, 2014, 03:22:18 am
content: It doesn't. But PoE equipment is orders of magnitude less common in terms of units sold so squeezing out every last cent in assembling it is counterproductive.

author: nctnico
author_rank: Super Contributor
timestamp: March 15, 2014, 12:19:29 pm
content: Another option is to go for a process where solder for thru hole is also applied as paste. I never used it but it does exist.

author: marshallh
author_rank: Unknown
timestamp: March 15, 2014, 03:01:15 pm
content: Look up Bob Willis' "Pin in hole reflow" PDF

author: johnnyfp
author_rank: Frequent Contributor
timestamp: March 15, 2014, 09:09:08 pm
content: Certainly a good read. And interesting. But.. The reason I'm looking for a non through hole version is to free up the underside real estate to keep the board smaller.It looks like I have no option anyway, which kinda sux, but what can you do. I will just have to live with my board being 7mm longer.

author: dumle29
author_rank: Regular Contributor
timestamp: March 15, 2014, 11:27:29 pm
content: You do get to pick larger, easier to populate components then i guess :/

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: March 16, 2014, 12:06:20 am
content: i found one on alibaba ,it says minimum order 1 .http://yuan-dean.en.alibaba.com/product/234295502-200773996/Surface_Mount_RJ45_Jack_With_10_100Base_T_Magnetics.htmlhttp://www.yuan-dean.com/category/rj45-magnetics.htm