What are Memory Modules?

What are memory modules?

Meet the Connector: Memory Modules

Memory modules provide temporary data storage for computers and servers. They give laptops or other devices the ability to access and retrieve information quickly for processing tasks.

Also known as RAM sticks, memory modules are essentially PCBs mounted with integrated circuits for random access memory.

Memory modules are easy to install and replace. Initially their designs were proprietary, developed by computer manufacturers for specific models. The increased demand for high-speed data applications eventually led to organizations such as JEDEC (Joint Electron Device Engineering Council) developing standards that allow memory modules to be used across systems, according to the specifications mentioned under each standard.

Amphenol Communications Solutions’ DDR5 connector with only 287 terminals addresses the resonance from the floating RFU pin 220 which resulted in a margin delta. Both RDIMM and UDIMM versions of the new DDR5 socket are tooled and available. The 287-terminal DDR5 connectors and 288-pin DDR5 SMT memory module connectors withstand high system-level shock and vibration testing module weight. The module card is easy to insert and extract. It supports a thicker multilevel motherboard, optimizes airflow, and meets environmental requirements.

Types of memory modules

According to Amphenol Communications Solutions, SIMM (single in-line memory module) was an early multichip memory module. It generally featured 30 pins and 70 pins with a 32-bit data path. DIMM (dual in-line memory module) replaced SIMM with a 64-bit data path. Unlike SIMM’s redundant contacts, DIMM has separate electrical contacts on both sides. One DIMM, therefore, can replace two SIMMs installed in in-line pairs.

RIMM (Rambus in-line memory module), an early DIMM generation, used a 184-pin form factor for a 16-bit bandwidth. Later, modern DIMMs that aligned with DDRs and other advanced memory standards addressed increased demand for high-speed and low-latency devices.

RAM is volatile memory, meaning it is lost when the electricity (power) is removed. This type of memory is very fast, but the data must be constantly refreshed due to capacitors losing their charge over time. The refreshing aspect of the memory is called DRAM, or dynamic RAM. In contrast, static RAM or SRAM is faster than DRAM because it doesn’t need the time to refresh each bit. It is also more expensive, but small amounts of SRAM are sometimes used in the DRAM package.

SO-DIMMs (small outline DIMMs) that provide nearly the same power and voltage ratings at half the size of regular DIMMs are still used in compact computing devices, such as notebooks. RDIMMs (registered or buffered memory modules) have a hardware register between DRAM and the memory controller. Unbuffered or non-registered versions are called UDIMMs. Due to their higher cost, RDIMMs are used only for critical applications like servers.

ATTEND’s DDR5 SODIMM modules feature higher memory speeds and increased bandwidth starting at 4800 MHz, as well as larger capacities compared to DDR4. These advancements enable faster data transfer rates and improved multitasking capabilities, resulting in smoother and more responsive computing experiences. DDR5 features on-die error correcting code (ECC) for enhanced data integrity and reliability. The DDR5 SODIMM socket is available in 262 pins and is half the size of regular DIMMs. The 126B series operate at lower voltage levels, which helps reduce energy consumption and heat generation, resulting in improved laptop battery life and lower cooling requirements for small form factor systems.

Design Notes

Standards: JEDEC standards allow memory modules to be used across different systems, according to the defined specifications. Memory standards have been updated from SDR (single data rate) to DDR (double data rate). DDR-SDRAM (double data rate synchronous dynamic random-access memory) provides twice the speed and greater efficiency of data transfer compared to SDRAM. DDR5 has significantly higher bandwidth, spanning up to 6400 MHz to outperform DDR4 at 3200 MT/s.

Distinguishing characteristics: voltage, capacity, speed (bitrate), and form factor.

Material specifications: Most DRAM is packaged in black epoxy resin.

Environmental requirements: Temperature ranges of 0 °C to +95 °C (commercial) and -40 °C to +95 °C (industrial); withstands high levels of shock and vibration

Markets and Applications

Datacom/Telecom

Laptops, notebooks, PCs, data centers. DDR5 with SO-DIMM has created opportunities for advanced notebooks, mini PCs, NAS (network-attached storage), and Industrial PCs.

Suppliers

Amphenol Communications Solutions, ATTEND, Infineon Technologies (available through DigiKey), Micron Technology (available through Mouser Electronics), and others.

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