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AM625: AM62 DDR4 2x8 CONFIGURATION question.

Paul Koudritsky
Prodigy 10 points

Part Number: AM625

Hi.

In our design we are using the 2x8 DDR4 configuration instead of 1x16 as on the eval board.

2 questions :

1) On the x8 DDR4 IC there is nTDQS signal ( BALL A3 ) , should it be used and connected to the CPU , if yes to what pin ?

2) The eval board schematics ( E1 and E2 )  does not have the suggested in the app note ( https://www.ti.com/lit/pdf/SPRAD06 )  ADDR_CTR lane termination resistors. So - should we have ? Does the fact that we are 2x8 increases the importance of the termination resistors ?

Another , not memory related question  - our LCD is MIPI , but the VDD is 1.8V . Digital inputs of the LCD have to be 1.8V ( this is clear ) , LVDS pairs - any affect of the voltage levels should be taken into configuration ?

Thank you.

  • 0
    TI__Guru* 95521 points

    1) The TDQS function is not used, so A3 can be left unconnected.  Be sure to connect the DM signal to the processor.  THis is muxed with the TDQS_t signal (ball A7)

    2) Yes, since the eval board is point to point, we have removed the on-board termination.  With 2 x8 in fly-by topology, VTT termination is a requirement

    Can you ask the LCD question on a separate email so it gets routed to the right person

    Regards,

    James