What Is LPDDR (Low Power Double Data Rate Memory)?
Understanding LPDDR Memory
RAM (Random Access Memory) is the main memory that directly influences the system’s performance. RAM is a type of computer storage that holds data temporarily. It stores the information from a program currently running or from an application’s recently opened file. RAM is volatile, meaning it loses its contents when the device shuts down or when power to the device is interrupted.
Computers have different types of memory followed by different data storage methods. This blog will focus on What Is LPDDR Memory, the Difference between LPDDR in Laptops and Smartphones, and the Types of LPDDR Memory.
What Is LPDDR
The LPDDR (low power double data rate) RAMs are designed for smartphones or other mobile devices. These RAMs are also referred to as DRAM or SDRAM. These mobile DDR RAMs transfer the data on a clock’s rising and falling edge. They can perform multiple cycles per second, unlike Single Data Rate and SRAM, which only transmits the data on one end or can perform one operation per second.
There are five generations of LPDDR RAM, with every RAM carrying significant improvements; for instance, DDR1 uses 2.5/2.6 volts, DDR2 consumes around 1.8 volts, whereas DDR3 use 1.5 or 1.35 volts, DDR4 uses 1.2 or 1.05 volts and DDR5 that is now widely used for commercial purposes, use 1.1 volts. The energy consumed by the RAMs hugely impacts the devices’ battery life. Therefore, the battery life is extended, and LPDDR RAMs were designed.
Difference between LPDDR in Laptops and Smartphones
LPDDR Memory is designed for portable/mobile devices, including Ultrabooks, MacBooks, and smartphones. Even though this Mobile Computer Memory uses the same technology in phones and laptops, the form factor and design of the DRAM chips vary as per the device, regardless of which generation of LPDDR it belongs to.
For instance, if we were to compare laptop LPDDR with a phone LPDDR, the difference between the two would become more evident as laptop LPDDR consists of a 64-bit wide memory bus whereas phones come with 16/32-bit data bus. Also, the packaging of LPDDR differs per the design and the pin density. Hence, the LPDDR RAMs are non-modular, which means that the RAM is in certain systems like MacBooks, UltraBooks, or smartphones.
Types of LPDDR Memory
LPDDR is a low-powered version of DDR standards that comprises significant changes with every new variant. These storage drives, despite being standardized by JEDEC, every LPDDR RAM has set its standards with enhanced performance and advanced features. These RAMs are designed to operate at low voltages and can cater to current and future mobile computing requirements. Unlike DDR, LPDDR RAMs offer 32-bit or 16-bit bus options for use cases with lower requirements.
Here’s a brief explanation to help you understand the differences and offerings of LPDDR Memory Types;
LPDDR 1 is slightly different from DDR1, with the main difference in energy consumption from 2.5 to 1.8 volts. The minimized energy consumption has reduced the temperature of DRAM modules resulting in less downtime. These memory modules also comprise the ability to refresh part of the array followed by deep power down mode. As far as the performance of LPDDR is concerned, that allows for a data transfer rate of 400 MT/s or 533.3MT/s with a prefetch size of 2n. Also, the speed of LPDDR1 usually ranges up to 266.7MHz, which is faster than was ever standardized in DDR1.
LPDDR2 version of LPDDR RAM is designed to operate at the voltage of 1.2 or 1.8V. Further, LPDDR2 RAM works at a double I/O clock speed of LPDDR1 with the speed of 400MHz or 533.3MHz. As for transfer rate, LPDDR 2 can transmit the data at the speed of 800MT/s or 1067 MT/s with the prefetch of 4n.
The main change featuring LPDDR3 was increasing the prefetch size to 8n, which boosted the data transmission speed around 1600 MT/s to 2133MT/s. This variation offers similar performance to DDR3. Also, the LPDDR3 version can operate at 1.2 to 1.8 volts.
LPDDR4 has the same standard as DDR4, with data transfer speed ranging up to 3200 MT/s which was later expanded to LPDDR4X which then offers an unmatched data transmission speed of 4267 MT/s. Furthermore, the LPDDR4 standard can operate at 1.1 or 1.8 volts, whereas LPDDR4X can operate at even lower power of 0.6 volts. LPDDR4 features significant changes, including doubling the prefetch size and changing the I/O bus from a single 32-bit bus to a pair of 16-bit buses.
LPDDR5 comprises more advanced features and even better upgrades followed by lower power consumption. LPDDR5 includes a data transfer speed of around 6400MT/s which was later further upgraded in the form of LPDDRX5 with a data transfer speed of 8533 MT/s, which exceeds the standard set by DDR5. The LPDDR5 version is expected to be available for mobile products in 2023.
To further clarify, here is a table that compares all these five generations of LPDDR5;
|I/O bus clock frequency (MHz)||200, 266.7 (For LPDDR-1E)||400, 533.3 (For LPDDR-2E)||800, 1067 (For LPDDR-3E)||1600, 2133 (For LPDDR-4X)||3200||3750/4266.5|
|Data transfer rate or speed in Mbps||400, 533.3 (for LPDDR-1E)||800, 1067 (for LPDDR-2E)||1600, 2133 (for LPDDR-3E)||3200, 4267 (for LPDDR-4X)||6400||8533|
|Supply voltage||1.8 V||1.2, 1.8 V||1.2, 1.8 V||1.1, 1.8 V | I/O voltage: 0.6V||1.05, 0.9 | I/O voltage: 0.5, 0.3||1.05, 0.9 | I/O voltage: 0.5, 0.3|
|Die Density||128Mb – 2Gb||256Mb – 2Gb||1Gb – 8Gb||4Gb – 24Gb||4Gb – 24Gb||8Gb – 24Gb|
|Memory Clock||200, 1E-266.7||200, 2E-266.7||200, 3E-266.7||200, 4X-266.7||400||400|
LPDDR is a series of RAM explicitly designed to be used in power-constrained environments. These RAMs are commonly found in smartphones, tablets, and some laptops. While the standards are based on the DDR standards, they are distinct and do not always make similar changes in the same generation. Therefore, the main difference is that LPDDR is standardized to run at lower voltages, as low as 0.5 volts. It also supports operation at 1.8 volts, which is higher than the 1.1-volt power standard of DDR5. However, it is not clear how much this portion of the LPDDR standard is used. Also, several other changes have been made to the LPDDR standards designed to reduce further power requirements, including numerous improvements to the refresh process.