Samsung Announces Production of 20nm Mobile LPDDR4, Faster Than Desktop DDR4 42
MojoKid writes Samsung announced today that it has begun volume production of its 8Gb LPDDR4 memory chips, with expected commercial shipments in 2015. The announcement is noteworthy for a number of reasons. First, one of the most important characteristics of a modern mobile device is its battery life, and moving to a new memory standard should significantly reduce the memory subsystem's power consumption. Second, however, there's the clock speed. Samsung is claiming that its LPDDR4 will hit 3.2GHz, and while bus widths on mobile parts are significantly smaller than the 64-bit channels that desktops use, the higher clock speed per chip will help close that gap. In fact, multiple vendors have predicted that LPDDR4 clock speeds will actually outpace standard DDR4, with a higher amount of total bandwidth potentially delivered to tablets and smartphones than conventional PCs will see. In addition, the power savings are expected to be substantial.
LP = low power (Score:2)
Re:LP = low power (Score:5, Funny)
So LPDDR4 means Dance Dance Revolution 4 played with a 33 1/3 RPM record, right?
The legend of DROP OUT (Score:2)
And how are going to "actually outpace standard DDR4", whose song "Drop Out" [youtube.com] is already 260 BPM, while keeping it danceable? (Oh wait, that's how [youtube.com].)
mobile vs desktop bus width (Score:5, Informative)
and while bus widths on mobile parts are significantly smaller than the 64-bit channels that desktops use
Many chips such as Snapdragon 805 and Apple A8x use dual-channel 64-bit LPDDR3 with about 25GB/s total memory bandwidth.
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What's with the clock rate masturbation? (Score:2, Informative)
I'm not sure why they're speculating on the whole "faster than desktop!". What's the agenda here? Higher clocks isn't actually a desired feature, it's what you have to do if the bus is too narrow and you're too cheap do make it wider. If they could afford it, they'd definitely pick a wider bus before higher clocks (and therefore more energy consumption).
Also, desktop DDR4 has been run at 4GHz already.
In short; good luck with that.
Re:What's with the clock rate masturbation? (Score:4, Informative)
Also, desktop DDR4 has been run at 4GHz already.
Perhaps by enthusiast overclockers, but the current DDR4 standard only goes to 2400MT/s with provisions for up to 3200 in a future revision of the spec.
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Higher clocks isn't actually a desired feature, it's what you have to do if the bus is too narrow and you're too cheap do make it wider. If they could afford it, they'd definitely pick a wider bus before higher clocks (and therefore more energy consumption).
It's not always cost that limits bus widths. See PCI for example. They tried widening it (64 bit) and clocking it up (66, 133, and very rarely even beyond), but what won out is a much higher clocked serial interface (PCI Express).
Skew in a parallel interface is a bitch, plus the number of traces required on the board to support a wide bus. There's only so many connections you can practically run in to any given chip package without getting unmanageable.
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It's a shame SRAM was left to rot and so much effort research & infrastructure has been poured into DRAM.
SRAM was not left to rot. It's in every CPU out there and is called cache memory. It is much more expensive than DRAM and that's why we only have a few MB.
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Uh.. just put it in your desktop (Score:1)
" In fact, multiple vendors have predicted that LPDDR4 clock speeds will actually outpace standard DDR4, with a higher amount of total bandwidth potentially delivered to tablets and smartphones than conventional PCs will see."
I doubt it since you could just adapt the LPDDR4 memory for use in a desktop if you have half a brain. Furthermore, since since sub-watt level powersavings aren't really critical on a desktop, if these chips are actually that good then they can be opened up to run faster at a higher po
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Samsung has some information about their packaging options here [samsung.com]. But yeah, they're not SODIMM or another kind of removable socket. They're all intended for integration into a system-on-a-chip (SoC), via either surface-mount [wikipedia.org] or package on package [wikipedia.org].
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Don't you think Samsung is talking about chips, and it is up to whoever uses those chips whether they are mounted permanently or on some sort of removable module?
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Re:PC with SODIMMs? (Score:4, Informative)
There are no DIMMs for LPDDR, SO or otherwise. The price for low IO power is no termination resistors. The means you only get adequate signal integrity with short, point to point traces. Edge connector buses need not apply.
SODIMMs use the same DDR protocol as desktop DIMMs, but usually contain fewer chips and wider buses to each chip.
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So what's a DDR3L (1.35V) SODIMM? I have no clue what the difference is between LPDDR and something like DDR3L, but you sound like someone knowledgeable enough to answer.
DDR3L is lower voltage but otherwise identical to DDR3. LPDDR is an entirely different line used mostly in cell phones. LPDDR3 has no relationship to DDR3, just as LPDDR2 had no relationship to DDR2 and LPDDR4 has no relationship to DDR4.