Reference design redesign

[almaz1c]

Hi!

We have working custom pcb with IMX6ULL based on reference design (number 29364) with only 9 components placed on bottom side of pcb:

There are DDR3 relative parts:

So, I am wondering can I move this components:

- C204 decoupling capacitor for DRAM_VREF;

- R202, R203, R205 resistors that ties to gnd DRAM_SDCKE1, DRAM_SDCKE0 and ZQPAD signals;

- R206 that terminates DRAM_SDCLK0_P and DRAM_SDCLK0_N signals (increases traces length);

- C227, C229, C228 and C230 that terminates DRAM_SDQS0_P, DRAM_SDQS0_N, SDQS1_P and SDQS1_N

little bit away from their current position to place them on top side of pcb? We want to reduce soldering price twice)

[igorpadykov · Accepted solution]

Hi Almaz

in general they can be moved, only pay attention to high speed signals

like DRAM_SDCLK0_P and DRAM_SDCLK0_N to avoid ringing and reflections.

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[almaz1c]

Seems that DRAM_SDCKE1 and DRAM_SDCKE0 pull down resistors not required at all:
https://community.nxp.com/thread/439876