What is SODIMM Memory | Features | Types | Use of SODIMM

RAM memory is a fundamental element in any computer equipment, since it is where the processor stores information.

There are different RAM memory standards as well as different formats. One of these formats is RAM memory “SODIMM” a format developed for laptops and small format systems.

See Also: Can we Use SSD as RAM

What is SODIMM Memory

It is a RAM memory format specifically designed for laptops, where space is at a premium. SODIMM is “just” a reduced version of a RAM memory module for a desktop computer.

Although SODIMM (Small Outline Dual In-line Memory Module) modules are used in systems where the amount of space is more limited.

Above all, SODIMM memories are used in laptops, but they can also be used in office printers, professional routers, NAS devices, embedded systems such as Intel NUC, among others.

SODIMM memory standards do not differ at all from “normal” module standards (DIMM format). By standards we mean DDR3, DDR4, DDR5 and any future coming standards.

See Also: What is LPDDR5 Ram

Features of SODIMM Memory

SODIMMs mostly have the same frequency, power, and voltage parameters (in some cases) as DIMMs.

They only differ in format and in the maximum capacity of the modules, which are being more compact.

The characteristics of the SODIMM modules according to generation are:

1. SDR SDRAM: This memory has a 100-pin version with two notches and a 144-pin version with one center notch. Currently they are already in disuse for being a very old format
2. DDR SDRAM or DDR2 SDRAM: These are characterized by having 200 pins and a notch near one of the sides. The exact location of the notch can vary between both formats. Currently they are already in disuse for being a very old format as well.
3. DDR3 SDRAM: It is characterized by having 204 pins and having a notch very close to the center
4. DDR4 SDRAM: It is the standard used today and is characterized by having 260 pins and the notch is located after pin 144. These SODIMM modules have dimensions of 69.6mm wide and 30mm high.
5. DDR5 SDRAM: It is estimated that the first systems with DDR5 SODIMM memories will arrive in 2022-23. These modules are characterized by having 262 pins and operating at a voltage of 1.1V, less than DDR4 SODIMM modules and maintaining the dimensions of this standard.

Different Types of SODIMM Memory

Let’s check below the different types of SODIMM Memory in detail one by one.

1. 200-pin SODIMMs

Something quite curious is that the 200-pin SODIMM modules can be for DDR and DDR2 type memories.

For both cases, the notch is in the following arrangement: 20 pins – notch – 80 pins. The notch on DDR2 memories is slightly offset towards the center of the module.

DDR and DDR2 modules are not interchangeable, integrating this notch to prevent cross installation.

This slight design modification is integrated to avoid installing memory in slots of different generations, since there is electrical incompatibility.

See Also: DDR4 vs DDR5 Ram Memory

DDR SODIMMs operate at 2.5V and DDR2 SODIMMs operate at 1.8V.

2. LPDR format

Physically a DDR SODIMM module and an LPDDR SODIMM module are identical, but there are some technical differences.

Although the LPDDR standard has existed since the first SODIMM versions, until the DDR4 standard arrived.

LPDDR is short for Low-Power DDR, which can be translated as low power DDR memory.

This low power version offers the same features and performance as a conventional SODIMM module, but with higher efficiency.

Not surprisingly, LPDDR SODIMM modules have been developed for laptops and systems where autonomy is critical.

Without going into excessively technical aspects, LPDDR4 memories offer a performance improvement of 50% and a consumption reduction of 40% compared to LPDDR3.

The regulator and standardized formats JEDEC published the standard on 25^th, 2014, with the main improvements being:

• The interface speed is doubled and numerous electrical enhancements are included, including a change in the I/O standard to a Low Voltage Swing Termination Logic (LVSTL) system.
• Introduces a doubling of the internal prefetch size and the minimum transfer size
• Changing the 10-bit DDR address/command bus to a 6-bit SDR bus
• Changing from one 32-bit wide bus to two independent 16-bit buses
• Automatic update is enabled by dedicated commands, instead of being controlled by the CKE line

In addition to these changes, this type of memory can be built in three different ways:

• Data and control lines are connected in parallel to a 16-bit data bus and a single chip that selects the connection independently per channel
• Two 32-bit wide half buses and control lines in parallel including chip selection
• Two independent 16-bit wide data buses

3. LPDDR4x

Different LPDDR4 standard have been developed by Samsung. The two SODIMM variants are technically the same, simply in LPDDR4x the I/O voltage (Vddq) is changed from 1.1V to just 0.6V. JEDEC published the LPDDR4x standard on March 8, 2017.

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In addition to a voltage reduction, there are some minor improvements. LPDDR4x allows the single channel die option for “simple” applications such as MCP, PoP and IoT packets.

Additional definition and timing enhancements are also added for the higher speed grade of 4266MT/s.

4. LPDDR5

LPDDR5 Standard published by JEDE on February 19, 2019 by introducing the following changes:

• Data transfer rate increases up to 6400MT/s
• Introduces differential clock signals
• Preload size is not multiplied again, remaining at 16n
• Number of banks increases to 16, but divided into four groups, something similar to what DDR4 offers
• Power saving improvements through commands to decrease data transfer and dynamic frequency and voltage scaling
• New clock architecture called « WCK & Read Strobe » (RDQS)

Differences between DIMM and SODIMM Memories

As they say, all thumbs are fingers, but not all fingers are thumbs. DIMM and SODIMM memories are RAM memory modules, but basically what changes are the dimensions. Regardless of markings, SODIMMs are half the size (approximately) of DIMMs.

See Also: What is ReRAM or Resistive Random Access Memory

DIMM modules are the typical memory modules for desktop computers (mostly accompanied by little lights).

The problem with DIMM modules is precisely that they are very long and this is a problem in systems where size scare.

Precisely SODIMM modules solve this problem, leaving additional space for other components. DIMMs have a standard length of 125mm, while SODIMMs have a standard length of 63m. But it’s not the only advantage of SODIMMs over DIMMs.

SODIMM memories are much more efficient, since they need to consume less to increase the autonomy of the system. SODIMM memories also have fewer connection slots, since there is less contact surface.

Additionally, in SODIMM modules, the pins are installed on both sides of the memories, it is as if we folded the pins of a DIMM module on themselves.

Use of SODIMM Memory

Above all, SODIMM memory is used for laptops, where space is really limited and many elements have to be integrated in the minimum possible space.

Its use has been extended to other systems, such as compact computers in the Intel NUC.

We can also find mini-ITX motherboards that use SODIMM memories, but in most cases, it is portable RAM.

They are also used for small development boards and embedded system boards. Some consoles also use SODIMM modules, mid-range and high-end NAS use SODIMM modules, and many other products.

Conclusion

The difference between SODIMM memories intended mainly for laptops and DIMM memories for desktop computers (and servers, among others) are minimal.

See Also: How to Calculate MT/sec Ram

Mainly SODIMMs are more compact, thinking about the space limitations that we find in laptops.

It also changes the number of pins and capacities a bit, since SODIMMs can accommodate fewer memory chips than DIMMs.

Perhaps the biggest variation of SODIMMs is in the LPDDR variants, which offer improvements in power consumption.

LPDDR modules are characterized by having much lower consumption than DDR modules (either DIMM or SODIMM).

The increase in energy efficiency is achieved by using some “tricks” that allow to reduce energy consumption by adjusting the variable frequency, although there are other mechanisms.

All in search of maximizing the autonomy of portable equipment, these modules can also be used in the other systems that we have mentioned that support SODIMM modules.

Now we want you to tell us, have you ever changed the RAM on your laptop?