obsolete RAM

[avion]

Hi robertferanec

The Ram MT41J128M16HA-15E TR is obsolete, is there another one that I can use without changing the design????

[avion]

In digikey the new version is MT41J128M16JT-125:K TR. I checked the datasheets and the pin layout and pin assignment are the same as the obsolete RAM MT41J128M16HA-15E.
As you can see I compared the RAMS in the image below, obsolete and the new version, and the only difference is dimension of the RAM Case, 8 mm width instead of 9mm, and faster Clock speed. So I assume I can just use the left RAM (new) without changing pcb?

[robertferanec]

I didn't check specifically the memory which you are suggesting, but Micron usually only changes revision number or speed. These chips are then usually compatible (no need to change PCB, but you may want to re-run calibration). Often you can also use 1.35V chips which are 1.5V compatible (Usually you will find in datasheet something like this: Backward-compatible to VDD = VDDQ = 1.5V ±0.075V)

[avion]

robertferanec I looked at the footprint of microns bigger rams and they are very similar such as the 2Gb vs 8Gb DDR3. Can we use 4GB of RAM, that is 4 x 8Gb chips on the same layout? Do you know a P/N for such RAM?

[robertferanec]

I know that VOIPAC sells the iMX6Rex modules with bigger RAM, but I do not know the exact part number: http://www.voipac.com/#iMX6-REX-53342211

[avion]

Yes Voipac offers different RAM sizes but are they using the same PCB layout of IMX6 Rex for all RAM sizes they offer? I have looked at the 2Gb, 4Gb and 8Gb Micron RAMs and it seems like the only difference occurs with address pins 2Gb (16K (A[13:0])) , 4Gb (32K (A[14:0])) and 8Gb (64K (A[15:0])). The IMX6 rex layout in the lessons have A14 and A15 nets also connected even though they are not used for the 2Gb RAM, so can we use the 8Gb for this same pcb as well?

https://www.micron.com/parts/dram/ddr3-sdram/mt41k512m16ha-107?pc={00EED26F-83AE-4CE6-9A28-EB8B033361E8}


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[robertferanec]

Yes, they use same PCB. Just be sure, that you buy RAM with 1 silicon (1 chipselect). There are many RAMs with two silicons (two chipselects) and this is not compatible with the PCB.