Low Power DDR2 memory for DM8168

Simon Brown

Hi,

I've got a very power sensitive design started, and was therefore hoping to use the new Micron LPDDR2 memory, (eg MT42L128M16D1) on my DM8168 design (planning to use DM8165 in production). What I am curious about is whether the LPDDR2 would be supported, given that the datasheet implies 1.8V for DDR2 and 1.5V for DDR3, but LPDDR2 is 1.2V. I haven't checked through all the details yet, but I assume that it would then follow most of the other DDR2 specs, and it seems to meet the specs re address/cs/clk lines etc.

I was wondering if I just applied 1.2V to the DDR_VDD pins and 0.6V to the DDR Vref pins whether it would work, or am I being grossly optimistic?

Cheers,

Simon

over 13 years ago

0 Simon Brown over 13 years ago

Intellectual 340 points

Ok, it would appear I was too quick at posting - the next read through of some of the datasheet implies that internal core of the LPDDR2 chips is 1.2V but external IO voltage is still 1.8V, so I shall assume that it will work, unless anyone has any advice to offer to the contrary. I'll do a lot more careful reading to make sure.

Out of interest, if this only runs at 400MHz or 533MHz is this likely to affect performance of the Video Encoder/Decoder engine and other functions, compared to the EVM which has 800MHz DDR3 memory on board?

Cheers,

Simon

0 MarcPyne over 13 years ago

TI__Mastermind 25055 points

Simon,

The DM816x only supports DDR2 and DDR3. You might consider using the DM814x which supports LPDDR.

Regards,
Marc

0 Simon Brown over 13 years ago in reply to MarcPyne

Intellectual 340 points

Hi Marc,

Thanks for your reply. Hadn't come across the DM814x until now, so thanks for the pointer. I notice that says it handles DDR2, DDR3 and LPDDR. My original post was about LPDDR2, just being released by Micron - is this likely to be a DDR2 interface where the memory chip core runs off 1.2V or are there subtle differences that would make it incompatible with the DM816x DDR2/3 controller?

Cheers,

Simon

0 Simon Brown over 13 years ago in reply to Simon Brown

Intellectual 340 points

Hi again,

Ok, must read things more carefully. Again. The VDDQ on the LPDDR2 chips is 1.2V, so you'd need a 1.2V I/O on the DM816x and a 0.6V reference. I assume this really isn't supported. Oh well.

Cheers,

Simon

0 MarcPyne over 13 years ago in reply to Simon Brown

TI__Mastermind 25055 points

Simon,

That is correct.

Regards,
Marc

0 Simon Brown over 13 years ago in reply to MarcPyne

Intellectual 340 points

Ok, thanks for clarifying. One further question:

The Micron website says that they work closely with TI and the OMAP35x processors, to make sure their memory works with those. Do TI currently support LPDDR2 with any of their processors, and when is it likely to be supported by a DaVinci processor?

Cheers,

Simon

0 MarcPyne over 13 years ago in reply to Simon Brown

TI__Mastermind 25055 points

Simon,

You might want to check out the processor selection tool:

http://focus.ti.com/en/multimedia/flash/selection_tools/dsp/dsp.html?DCMP=Embd_Prs_Slctn_Tool&HQS=Other+OT+dspseltool

Regards,
Marc

0 Simon Brown over 13 years ago in reply to MarcPyne

Intellectual 340 points

Hi Marc,

Lovely selection table. Shame it doesn't list either the 8148 or 8168 as options! :-)

Cheers,

Simon

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Low Power DDR2 memory for DM8168