Web Survey: LP DDR and DDR3 DRAMs

LP DRAMs and PC DDR3 DRAMs: Vendors’ Portfolios Fill out Slowly (LP) and Rapidly (PC): For a customer inquiry, we generated the following survey table of DRAM devices whose data sheets were posted on their respective company websites, for LP DDR 1 & 2 and DDR3 DRAM products. It includes the basic “we offer/do not offer” product information, plus some additional detail about some vendors’ particular offerings that are different from others. Here’s the table and below it is a short discussion of trends and findings:

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LP DRAMs:
All major DRAM makers supported the basic LP DDR1 product set, though only Samsung (1Gb) and Micron (512M) showed LP DDR1-400 on their website; the rest stopped at either -266 or -333. Other vendors have announced LP DDR1-400s, but these are apparently not web-worthy yet (i.e., not ready to take production orders).

Supported densities for these LP DDR1s were 128M to 1Gb, with Hynix having a 2Gb device (announcement only, not on web ‘short form’).

No vendor showed an LP DDR2 product offering on its website, though Hynix, Elpida and Samsung have had press announcements of such parts in 2008. For sure, “web status” constitutes some high level of certainty that the design is stable, and the vendor is confident that it can be taken to market and ramped into volume production...so we have to conclude that ‘we are not there yet' with LP DDR2.

But, for sure, 2009 should be the year that LP DDR2 really starts to take root, but, lest we get ahead of ourselves, we should note that it was not until mid-2008 that LP DDR1 finally grew past SDR-based LP DRAMs to achieve 50% coverage of the Low-Power DRAM space. The originally-proposed three year and one architectural generation delay between the PC DRAM take-up, and that of the LP DRAM seems to have been extended, but also the take up of DDR3 is delayed (again)...combining to delay advanced LP DDR DRAM versions

Commonly, LP DRAM operating temperature ranges were -40C to +85C, with a smattering of product that ran up to +105C from Micron.

DDR3 DRAMs:

Most DRAM makers are on their third (or more) DDR3 die revisions, and it has been FOUR years since Samsung first showed working silicon for DDR3 in 2/05. There have been two or more false starts by Intel to push or draw DDR3 into the market, but it was only last month ago they again delayed their DDR3-only chipset from this coming spring 2H09. This leaves designers still with a choice of DDR systems with those 80 cent 1Gb DDR2 DRAMs or moving on to DDR3, which still costs 2-3x more, and are only weakly supported at the breakaway speed of -1333.

As expected, the seminal DDR3 density, 512M, is now almost an orphan, though a few makers still support it. The real action starts with 1Gb, most vendors also offer 2Gb versions, and three vendors offer a 4Gb in a reach technology. The ranks of -1600 speeds are still incomplete: Samsung, Hynix, Elpida...yes; Micron no. Qimonda, NA. (Aftermarketers, like Corsair, which buy wafers and test to more aggressive specs, offer DDR3-2100s from the same die as is sold at -1600 by mainstream vendors. This is probably a “chicken and egg” problem, as few applications are designing to the -1600 spec, and the spec itself was delayed from the other speeds by a year or more it took to work out the datasheet details.)

There is universal support for x4, x8 and x16 versions for all DDR3 parts shown on vendor websites.

Operating Voltages Headed Down:
One trend that is worth watching is how fast the industry fills out the ‘reduced voltage’ PC DRAM and LP DDR DRAM portfolio. For about a year, spottily at first, momentum has been building to propose an alternative lower operating voltage roadmap for both PC DRAMs and LP DRAMs. By original conception, LP DDR1 DRAMs run at 1.8V, LP DDR2 DRAMs are 1.5V and PC DDR3 DRAMs at 1.5V operation. But in viewing the websites, many vendors are offering reduced-voltage parts, which can give lower power and still hit the performance specs. Today, these include PC DDR3 DRAMs operating at 1.35V (and down to 1.2V), and LP DDR2 DRAMs, also at 1.35V. This part of the spec landscape is very much a moving target, and there is no guarantee that subsequent generations of designs and the mix of usage will operate at 1.2V...or even lower.