Jun 27, 2019
03:39 AM
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Jun 27, 2019
03:39 AM
Hi Infineon,
at Relaxkit 4500 Rev1.2 the TX connections from phy (IC200) to RJ45 (X200) are interchanged, TXP is connected to TD- and TXM to TD+. Please is there any reason for or is this an error?
Best Regards
Wolfgang
at Relaxkit 4500 Rev1.2 the TX connections from phy (IC200) to RJ45 (X200) are interchanged, TXP is connected to TD- and TXM to TD+. Please is there any reason for or is this an error?
Best Regards
Wolfgang
2 Replies
Jul 10, 2019
08:42 AM
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Jul 10, 2019
08:42 AM
Hi,
I would advise to follow Design Checklist at https://www.microchip.com/wwwproducts/en/KSZ8081.
Regards,
Jesus
I would advise to follow Design Checklist at https://www.microchip.com/wwwproducts/en/KSZ8081.
Regards,
Jesus
Jul 11, 2019
01:12 AM
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Jul 11, 2019
01:12 AM
Hi Jesus,
thanks, the checklist says:
"MDI Connections: Pin 1 of the RJ45 is TX+ and should trace through the magnetics to TXP (pin 7) of the KSZ8081RNB. Pin 2 of the RJ45 is TX- and should trace through the magnetics to TXM (pin 6) of the KSZ8081RNB."
So there is no reason to interchange the tx connections.
But TX+ connected to TXM and TX- to TXP only results in a phase change by 180 degr, at clock frequency of 125 MHz (100 MBit/s) and a wavelength of about 2 meters in the cable it's like a cable length difference of 1 meter between tx and rx line. This doesn't affect the clock recovery in the phy, it will compensate this phase difference, so this 'wrong' connection also runs.
Best Regards
Wolfgang
thanks, the checklist says:
"MDI Connections: Pin 1 of the RJ45 is TX+ and should trace through the magnetics to TXP (pin 7) of the KSZ8081RNB. Pin 2 of the RJ45 is TX- and should trace through the magnetics to TXM (pin 6) of the KSZ8081RNB."
So there is no reason to interchange the tx connections.
But TX+ connected to TXM and TX- to TXP only results in a phase change by 180 degr, at clock frequency of 125 MHz (100 MBit/s) and a wavelength of about 2 meters in the cable it's like a cable length difference of 1 meter between tx and rx line. This doesn't affect the clock recovery in the phy, it will compensate this phase difference, so this 'wrong' connection also runs.
Best Regards
Wolfgang