01-11-2019, 03:32 PM
(This post was last modified: 01-11-2019, 03:39 PM by WrongWorld.
Edit Reason: Spelling
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(01-10-2019, 10:03 PM)4_4t Wrote: > I am thinking about trying with the 1.2V
Is it a 2.5v mistake ?
Yes, it's a mistake, I meant 2.5V, but I am by now aware that 2.5V is above the maximum voltage supported by the integrated PHY.
(01-10-2019, 10:03 PM)t4_4t Wrote: That is the same constitution as "mbed-005.1.pdf".
1.8v already exists on the rock64 board.
Connect 4 terminating resistors directly to that node.
In this case, neither a regulator taking up space nor a capacitor is required.
I already tried it actually.
Tried "ROCK64" model is only "RAM=4G". (which had less margin of Ethernet)
In addition, I do not plan to check with all the "ROCK64" that i own.
And it worked.
However, in order to operate stably,
Separate "C"=(0.1 uF) was required for "TD_TCT / RD_TCT" respectively.
But, it is not a big increase in size. (+ 0.1uF x 1)
It will be possible to place on the back of the "RJ45"
While I had the same idea of getting 1.8V straight from the board, since it's already there, I failed to find the right spot where to solder a cable. I tried to follow all the VCC_18 lines in the Rock64 schema (stemming from RK805-1), but I haven't found one point on the board where I would be able to get the needed voltage. To be honest, I have zero experience in soldering on SMD circuits, and I haven't a soldering station suitable for this task (I have a decent soldering tool, but good only for non-SMD components). It's also clear that your knowledge on the matter is way beyond mine
Your last sentence on where to put the double caps is not the problem for me (also it is suggested everywhere to have them as close as possible to the RJ45 port). It's the rest that is making me scraping my head, even more because I cannot locate the voltage regulator that you've suggested. It may be possible that this 1.8V voltage regulator is available in my zone (I'm not so sure, I'll have to ask), do you think it could be compatible? It can also work (and it seems that the manufacturer suggests it) with ceramic caps instead of electrolytic, which may help in finding a place for them.
MCP1702-1802E/TO
Thanks a lot again for all the useful info you've shared with us!
