Tool/software:
Hello,
I'm currently using one board with two DP83822 PHYs that is plugged to the small carrier board with the connector and the Magnetics.
I want to use multiple of these boards in series (EtherCAT) and I'm wondering if I can remove the Magnetics block between PCB1 & PCB2 and PCB2 & PCB3 ?
Thanks!
Milos
Hi Milos,
It's possible to operate DP83822 without magnetics/transformer on MDI lines.
For more details on this, please refer to this application report:
https://ti.com/lit/an/snla088a/snla088a.pdf
DP83822EVM also has options for transformer-less operation, for an additional reference.
Thank you,
Evan
Hi Evan,
I have a few questions:
1. The link you posted seems to be applicable only to:
DP83848C DP83848Q-Q1
DP83848I DP83849C
DP83848YB DP83849I
DP83848M DP83849ID
DP83848T DP83849IF
DP83848H DP83620
DP83848J DP83630
DP83848K DP83640
DP83848VYB
I don't see DP83822 here, can you confirm that this application note would work for DP83822?
2. If I understand correctly, I just need to add one capacitor in series (33nF, 100V) and to remove 1.8V from the pin 14 on the PHY side (AVD pin)? Should I leave that pin floating or connect it to GND?
3. Are the pull up resistors on the PHY side necessary? If yes, what value should I use? Also, what value for the capacitance between PHY's 3V3 and GND should be used?
Thanks!
Best,
Milos
Hi Milos,
Similar principle in application report applies to DP83822.
Please refer to DP83822EVM schematics here ("3.2 Analog Front-End Schematic"):
https://www.ti.com/lit/ug/snlu179/snlu179.pdf
For transformer-less operation, T2 is DNP'd, and C47 - C50 are populated.
Pull-up resistors are required on MDI lines (50 ohm).
Please let me know if the schematic clarifies the required network for this.
Thank you,
Evan