DP83826I: DP83826I with J1012

Tyler Holmvik

Part Number: DP83826I
Other Parts Discussed in Thread: DP83826EVM

Tool/software:

Can I please get help with following question:

I am working on schematic design with DP83826IRHBR as ethernet PHY. RJ45 connector J1012F21CNL from Pulse Electronics.

J1012 has different transformer topology than DP83826I datasheet figure 8-2, specifically for receiving path. Can this connector be used with DP83826I? J1006 from the same datasheet matches DP83826I datasheet figure 8-2. Both J1006 and J1012 have the same insertion loss, crosstalk and etc specification. If J1012 can be used, how do I connect center taps (pin 2 and 5) of transformer facing PHY?

Thanks,

Tyler

3 months ago

+1 David (ASIC) Liu 3 months ago

TI__Guru**** 179981 points

Tyler

Pin 2 should be connected to the PCB ground using a 2nF capacitor and pin 5 should also be connected to the PCB ground using a 2nF capacitor separately.

Thanks

David

0 Tyler Holmvik 3 months ago in reply to David (ASIC) Liu

TI__Intellectual 991 points

Thanks. Any risk in using 2.2nF cap instead? Is standard X7R cap OK or C0G better?

Tyler

+1 David (ASIC) Liu 3 months ago in reply to Tyler Holmvik

TI__Guru**** 179981 points

Tyler

The capacitor is for additional filtering purposes, each center taps for the pairs use the capacitors to prevent any stray current flow between each pair. So the selection of center tap capacitors of the transformer is mainly used for EMC performance. It does not affect the normal functionality of the PHY.

I do not see an issue of using X7R, this is what is being used on the DP83826EVM. Please make sure the capacitor has a +/- 1% tolerance.

Thanks

David

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DP83826I: DP83826I with J1012