It's that time again when we're getting yet another letter to add to the ones we already love and cherish when it comes to memory acronyms and this time it's the letter m and it's quite suitable that it comes from Micron then, in the shape of its DDR3Lm memory. What DDR3Lm memory brings to the table is reduced self-refresh power draw, something that should help improve the battery life of mobile devices.

It's that time again when we're getting yet another letter to add to the ones we already love and cherish when it comes to memory acronyms and this time it's the letter m and it's quite suitable that it comes from Micron then, in the shape of its DDR3Lm memory. What DDR3Lm memory brings to the table is reduced self-refresh power draw, something that should help improve the battery life of mobile devices.

Presumably the m stands for something like mobile, as the DDR3Lm memory intended for use in notebooks and tablets, although Micron seems to have forgotten to mention that part in the press release. The trick here though is what's called “low self-refresh power” something that can potentially save a fair amount of power, depending on the usage scenario.

One of the downsides of RAM, no matter the type used today, is that it needs to continuously self-refresh, as otherwise it will lose charge in the capacitors when the memory isn't being accessed. This in turn would mean that data held in the RAM would be lost. This is an oversimplification of how things work, but explains the basic principle here. Although we're only talking mW's here per DRAM chip, higher capacity chips use more power for the self-refresh.

According to Micron's own spec sheets, its DDR3L 1333MHz memory has a self-refresh current of 6mA and at 1.35V this gives us about 8mW. The significant thing here is that Micron claims that its DDR3Lm memory managed to improve upon this by up to 50 percent, so in other words DDR3Lm memory should have a self-refresh of about 4mW, calculated on a 1Gbit chip at 1333MHz. The smallest DDR3Lm chips are 2Gbit though and these are expected to be operating at 1600MHz. As the speed and size increase, so does the self-refresh power draw.

Micron will also have 4Gbit parts with speeds of up to 1866MHz and here the company has specified a self-refresh current of 3.7mA or less than 5mW. It might seem like a trivial power saving, but it all adds up when you're running on battery power. Of course the self-refresh power draw only matters when the memory is in standby mode, but considering how often computing devices are left idling, or in standby power mode, this is a way to reduce useless power draw. The new DDR3Lm memory chips will be made using Micron's 30nm class DRAM manufacturing process and the company is expecting to start shipping DDR3Lm chips in Q2, although the company is already sampling chips to its partners.

Source: Micron