Hello,
I am watching a connection diagram of LS1021A-twr.
A terminating resistance of CLK of DDR3 of P1010RDB is just between± 100 Ω.
LS1021A-twr adds a condenser to 72 Ω of resistance, and is connected to GVDD.
Is this circuit the specification of LS102xA? Or is there a different reason?
In particular, I can't understand the reason that a condenser exists by this circuit.
Best Regards,
Maaski.Uno
Please provide picture of the termination in question.
Dear ufedor,
The circuit I'd like to know is at the red arrow.
Further, I make a mistake, and 2 has turned the same question.
I'm sorry.
Best Regards,
Maaski.Uno
Please refer to the section "Termination Topology" in the following application note:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/4085
Concerning R231 and R232 values I believe that they were obtained during the layout simulation.
Dear ufedor,
Thank you very much for your answer.
I read document of the answer I received from you.
By the way, why is there C157 in this circuit?
Is this here to remove noise?
Best Regards,
Maaski.Uno
The capacitor provides a low impedance to ground for any common-mode noise induced on the diffrential pair.