Author Topic: 1000Base-T MagJacks, no. of cores, LED colours  (Read 710 times)

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Offline Northy

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1000Base-T MagJacks, no. of cores, LED colours
« on: October 19, 2020, 01:44:33 pm »
I seem to have spent all morning looking at Magjacks!  |O Who knew there was so much to them?  :-//

Can someone please explain the difference between the number of cores? The two popular ones seem to be 8 or 12 cores per port.

Is there a standard conversion for LED colours at all? I need to signify 10/100 or 100Base-T link/activity.

Thanks,

G
 

Offline Miyuki

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #1 on: October 19, 2020, 01:52:36 pm »
There is no real convention
Same with activity signalisation
Every big company have its own way
 

Offline phil from seattle

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #2 on: October 19, 2020, 03:37:34 pm »
Funny, I've spent the last couple of days doing the same though my goal is to figure out the best magjack for manufacturing a board in china.  I was really hoping to find several that have the same pinout (for manufacturing flexibility) but even within a single manufacturer, the pinouts seem to all be different. I was also hoping to find horizonal entry and vertical entry jacks with the same pinout as I have some customers asking for each but no love there.  Hate to have two different PCBs but it looks like that's going to be the case.  sigh.
 

Offline niconiconi

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #3 on: October 19, 2020, 03:52:53 pm »
Can someone please explain the difference between the number of cores? The two popular ones seem to be 8 or 12 cores per port.

There isn't much of a difference, the only difference is that the 8-core magnetics only have a group of common-mode chokes for EMI suppression, but the 12-core magnetics have both a group of common-mode choke and a group of center-tapped autotransformers to suppress EMI better (both are common-mode noise suppressors). A 12-core Magjack is usually recommended due to its better EMC performance. But if you must use a 8-core version, it should work too.

The 8-core magnetics basically has:

CM Choke (x4) - 1:1 Transformer (x4) - Connector

And the 12-core magnetics:

CM Choke (x4) - 1:1 Transformer (x4) - Autotransformer (x4) - Connector

Check this Application Note from MicrosemiMicrochip: https://www.infinite-electronic.my/datasheet/29-VSC8540XMV-03.pdf
« Last Edit: October 19, 2020, 04:04:55 pm by niconiconi »
 

Offline Northy

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #4 on: October 19, 2020, 09:14:52 pm »
Thanks for all the replies so far  8)

Looks like I want to find a 12 core part then.
I feel a bit like I've gone round in circles today.

What colour LEDs do people think are sensible?
The switch IC I'm using is designed to drive a bi-colour LED to show 10/100/1000 connection and activity all on the one (bi-colour) LED!

G
 

Offline Northy

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #5 on: October 20, 2020, 08:14:21 am »
I got a reply back from a connector manufacturer:

Currently. we will not promote 12 cores / 1000 base-T part to customer side. Since 8 cores’ design performance can have the same performance and have price competitive.

So, what are peoples feelings on 12 cores? Does no-one actually use them in reality?
With good layout etc is 8 core generally ok?

G
 

Offline NANDBlog

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #6 on: October 20, 2020, 08:31:28 am »
I got a reply back from a connector manufacturer:

Currently. we will not promote 12 cores / 1000 base-T part to customer side. Since 8 cores’ design performance can have the same performance and have price competitive.

So, what are peoples feelings on 12 cores? Does no-one actually use them in reality?
With good layout etc is 8 core generally ok?

G
https://www.we-online.com/catalog/media/o119947v446%20Tutorials_High%20Performance%20Low%20EMI%20Series_EN%20(rev1).pdf

If you check the CMR and other graphs, you will see that the 12 core versions have higher attenuation in the 100MHz-500MHz range. 8 core might fail the EMC susceptibility tests, the 12 core might pass.
 

Offline Northy

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #7 on: October 21, 2020, 08:25:28 am »
Does anyone here use magjacks in products?
Do you se 8 core or 12 core?

Thanks,
G
 

Offline Ranayna

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #8 on: October 21, 2020, 10:16:56 am »
Regarding LED colors:
In networking gear i almost always see orange for 10/100 and green for 1000 as link speed indicator. In clients it is generally green for 1000 as well, but i don't recall when i saw a gigabit capable client only using 10/100.
For activity it is green as well, most of the time.
Offhand, i can't name a specific device that uses different colors.
« Last Edit: October 21, 2020, 10:18:30 am by Ranayna »
 
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Offline Scrts

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #9 on: October 21, 2020, 02:53:59 pm »
Please be aware that some MagJacks are for PHY voltage outputs and some are for current outputs. I've made that mistake once... I highly recommend checking with the PHY supplier what are the recommended MagJacks or look into reference designs.

As for the colors, I usually like 1 or 2 Dual LEDs, so you can change color depending on link and/or activity.
 
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Offline Northy

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #10 on: October 21, 2020, 06:53:18 pm »
Thank you both for the replies.
Have you had success passing EMC testing with 8 core parts?

G
 

Online S. Petrukhin

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Re: 1000Base-T MagJacks, no. of cores, LED colours
« Reply #11 on: October 23, 2020, 08:35:03 pm »
Thank you both for the replies.
Have you had success passing EMC testing with 8 core parts?

G

Personally I like: led1 green-link (regardless of speed), led2 yellow-flashing activity.
And sorry for my English.
 


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