AM335x and DDR3-1333 at 400MHz DDR_CK

takeshi matsuzaki

Expert 2030 points

Hello,

My customer wants to use AM335x and DDR3-1666 at 400MHz DDR_CK.
They knows about the compatibility of DDR3 device speed grade and DM335x, that is
DDR_CK=3.3ns : DDR3-800
DDR_CK=2.5ns : DDR3-1600.
We explained that using DDR3-1666 at 400MHz DDR_CK is out of warranty, and they accept "out of warranty".
But they intends to validate DDR_CK 400MHz with DDR3-1666 even if it is out of warranty, because of the cost.

We are asked that what kind of validation is needed from them.
- change the DDR_CK up and down configuring the PLL in AM335x ?
- chnage the VDDS_DDR of AM335x ?
- give the hot air using drier ?

What kind of validation is needed ?

Thank you for any help you can provide.
Takeshi Matsuzaki

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi Takeshi-san,

This is not quite correct. For 400MHz DDR3 clock frequency the minimum requirement is DDR3-1600. DDR3-1666 your customer wants to use exceeds this requirement, therefore it should work with no issues. Please refer to Table 7-58 in the AM335X Datasheet Rev, G for details.

0 takeshi matsuzaki over 9 years ago in reply to Biser Gatchev-XID

Expert 2030 points

Hi Biser-san

I'm very sorry, this is typo!
Exactry DDR3-1333, not DDR3-1666!
My customer wants to use AM335x and DDR3-1333 at 400MHz DDR_CK.

Best Regards,
Takeshi Matsuzaki

0 Biser Gatchev-XID over 9 years ago in reply to takeshi matsuzaki

TI__Guru**** 393215 points

I have corrected the thread title and asked the factory for clarification about Table 7-58 requirements.

0 takeshi matsuzaki over 9 years ago in reply to Biser Gatchev-XID

Expert 2030 points

Thank you Biser, It's very kind of you.
I think it's tough to get advices from factory team, any little thing would be OK.
Best RegardsTakeshi Matsuzaki

0 Biser Gatchev-XID over 9 years ago in reply to takeshi matsuzaki

TI__Guru**** 393215 points

My personal feeling is that this may be a typo in the datasheet. I think that the minimum requirement should be DDR3-1066, not DDR3-1600, but again this is my personal opinion and I have asked for clarification, because I may be missing something.

0 peaves over 9 years ago in reply to takeshi matsuzaki

TI__Guru 55265 points

When the AM335x device was being designed, DDR3 memory availability was discussed with the major memory vendors and TI was told all future DDR3 devices shipped would be DDR3-1600 or faster. Therefore, the DDR3 interface on AM335x was timing closed to operate with DDR3-1600 or faster speed grade memory devices.

0 takeshi matsuzaki over 9 years ago in reply to peaves

Expert 2030 points

Hello Paul,

I know the circumstances of why AM335x was timing closed to operate with DDR3-1600, so I explained
using DDR3-1333 at 400MHz is out of warranty to my customer.
They want to use it even it is out of warranty.

again, we are asked what kind of validation is needed to check DDR3-1333 works at 400MHz.
- change the DDR_CK up and down configuring the PLL in AM335x ?
- chnage the VDDS_DDR of AM335x ?
- give the hot air using drier ?

Sorry for asking such an unreasonable question, but I'd appreciate it if you could show some suggestions.

Regards,
Takeshi Matsuzaki

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AM335x and DDR3-1333 at 400MHz DDR_CK