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Hello all,
The DP83826E on our PCB is not working with 100Mhz, basically, be able to be linked with a router but never could get the ethernet work with 100M. Ping or Lwip all failed with 100M, but 10M works.
1) I found the TP_p/n and RD_p/n have a step or oscillating behavior. is this the design of 10M preform?
And, when linked. offset of TP is ~1.8V, but that of RD is 1.0V on our PCB.
2) I found the Voltage of Cext is 1.64V on EVM board, but 0.8V on our own PCB. will it be saying something. should I change the Cext to higher to try (Now is using 2nf as datasheet).
Anyone please help to check.
Yes, we spent many time on this, still did not found root cause.
Could you have a look my problem and give us some suggestion? I checked DP83826EVM board, the TD and RD offset both are ~ 1.7V, but our PCB is showing 1.8V TD and 1.0V RD after the link is built on 100M.
What will be cause? all schematic just same as EVM, expect I use a transformer integrated RJ45, but with totally same parameter as the separated one in EVM as well.
I saw datasheet about power up sequence, Pedestal Voltage need less than 0.3V. Only thing I could suspect now is this.
We checked and compared all registers. this is the ones different, others are all same.
