Samsung has announced early production on 8Gb (1GB) LPDDR5 modules using 10nm-class* process nodes and with a specific focus on 5G and automotive applications. The new memory will feature a maximum transfer speed of 6,400Mbits/s with much lower VDD (LPDDR4 specifies a supply voltage of 1.1v; LPDDR5 can operate with a VDD of just 0.5v).
Keep in mind, however, that the voltage targets shown above are for the standard, not for any specific IC. According to Samsung, its memory will use a higher VDD — 1.1v for operation at the 6,400Mbit/s performance level, and 1.05v for a lower 5,500Mbit/s bandwidth. Both of these would be an advance over LPDDR4, but not nearly as dramatic a shift as one might see if you binned your LPDDR5 specifically for low power and minimal performance. Samsung also claims that its performance improvements are the result of internal design improvements. The company writes: “By doubling the number of memory “banks” – subdivisions within a DRAM cell – from eight to 16, the new memory can attain a much higher speed while reducing power consumption. The 8Gb LPDDR5 also makes use of a highly advanced, speed-optimized circuit architecture that verifies and ensures the chip’s ultra-high-speed performance.”
Power efficiency has been maximized by configuring the chip to lower its voltage in response to the operating mode of its application processor, and to avoid overwriting cells with ‘0’ values when in active mode. A new “deep sleep” mode is also available, which supposedly cuts power consumption to half of the current idle mode available in LPDDR4X. Overall, Samsung projects that the new LPDDR5 memory should be up to 30 percent more power efficient.
One oddity about all this is that LPDDR5 doesn’t seem to be particularly well-attested in the current public record. Typically by the time a new memory standard is poised for introduction, it’s easy to find no end of discussion concerning the spec. That’s not the case here. In fact, JEDEC doesn’t even appear to have finalized the LPDDR5 spec yet, which makes this a rather significant case of jumping the gun. DDR5 hasn’t even been finalized yet, and we’d expect the DDR mainstream version of the standard to appear before later low-power variants.
With data rates this high, LPDDR5 should be capable of sustaining up to 50GB/s of bandwidth in devices where 64-bit memory buses are common. That’s high enough to give PCs a run for their money at least in raw bandwidth — in practice, the very different memory structures, higher core counts, and large caches on PC SoCs make their memory subsystems significantly different from smartphones or tablets.
* – 10nm-class is Samsung-speak for “Not 10nm.” The company’s formal definition is “a process node between 10 and 20 nanometers.”
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