What is NAND Flash Memory? Definition and FAQs

Aaron Paul updated on Aug 24, 2022 to Knowledge Center

NAND flash memory is a common aspect of storage devices nowadays. So, what exactly is it?

NAND Flash makes your storage runs faster. It's a type of storage technology that doesn't consume any power to retain or requisite data. That's why it's one of the key tools available on every storage nowadays, particularly SSDs and pen drives.

NAND flash memory

So, what exactly is NAND flash memory? How does it work, and what purpose does it serve in a storage device? And, are there any types of it? So, let's answer all our questions by understanding what NAND technology is and how it helps with viable storage in modern technology.

What Is NAND Type Flash Memory?

NAND flash memory is a non-volatile storage type that doesn't require additional power sources to contain data. One of the main features of NAND Flash is its size, which is comparatively smaller than other storage types like Hard Disk Drives.

NAND Flash

NAND Flash devices/memory also don't take any power to store or pass around data. This makes NAND devices much quicker and nimble in shifting or moving data. So, where exactly is its use? In various devices, such as:

  • USB Pen drives
  • Solid-state drives (SSDs)
  • Storage of a smartphone, smart TV
  • NVME drives (type of SSD)

Since NAND flash also employs AI heavily, anything with the latest storage technology is bound to feature it in some capacity. Since most storage devices today feature it, the generations might change, but the use of NAND remains constant.

How Does NAND Flash Memory Work?

NAND Flash has a limited ability to read and write cycles in each block. In other words, every time you use it to write data, it eases and rewrites the new data in a continuous erase/write cycle.

However, the primary blocks of NAND flash work in mechanical shock resistance and high durability. In other words, they are able to fend off high pressure and operating temperatures compared to SSDs without NAND or basic hard disk drives.  

The two main types of NAND are 2D NAND and 3D NAND. Both these types have a few differences, such as:

2D NAND 3D NAND
128gb Max capacity 256/512gb but no max capacity
Floating gate design Floating gate and charge trap design
Low endurance High endurance (less cell-to-cell interference)
Comparatively slow performance Fastest performance today
High power consumption Low power consumption

The difference shows that the latest version works much faster, draws much less power, and works more efficiently. On top of that, it has much more capacity and performance headspace.

What Is The Difference Between NAND And NOR Flash Memory?

The key differences between the two architectures are their bit line and source line support. For example, the NAND Flash follows this architecture:

  • Bit Line > Bit Line Select
  • Word Line
  • Memory cell
  • Two Additional Grids
  • GND Line Select
  • Source Line

It all works from top to bottom, while Bit Line connects them. As for NOR Flash memory, the architecture goes like this:

  • Bit Line – Source Line
  • Word Line
  • Memory Cell
  • Four Grid Lines
  • Carry on to the bottom

For instance, here's a diagram to help you grasp this idea better:

NOR & NAND Flash
Image credit: embedded.com

As you can see, the Bit Line & Source Line work simultaneously in flash architecture. However, another key difference between the two architectures is the power consumption. For instance, NOR Flash memories require much more power than NAND during the initial stages.

While NAND Flash is known to have a little less stable current than NOR Flash. Rapid power is supported by both devices (for higher performance), but the active power is determined by the time each type remains active.

So, while NOR Flash has a certain advantage in random reads, NAND Flash is much more power-adequate in terms of reading, writing, and sequential read operations. Hence, the cooler operations at higher speeds are achieved by NAND Flash devices.

What Is The Best Type Of NAND Flash?

There are a few types of NAND Flash, and each one is used in various devices, such as SATA SSDs, NVMEs, and Flash Drives. So, which one of them stands out as the most well-rounded performance?

Here’s a comparison:

NAND Type Bits Data Retention (Average) Read/Erase* Programing Time (Average) P/E Cycle
SLC 1 10 Years 25 µs/2ms 200 µs 100,000
MLC 2 1 Years 50-60 µs/3-4ms   1.2ms 3000
eMLC 2 1 Years 50-60 µs/6ms 2ms 10,000
TLC 3 1 Years 105 µs/10ms 4.65ms <1000

*µs = Microseconds

As you can see, SLC NAND isn't only the fastest, it's also the most efficient. On top of that, it has unmatched durability because of its advanced algorithms and capabilities to handle power stages.

Thus, these factors make SLC the primary NAND flash type in today's devices. And, if you're looking for one with NAND Flash, then always go with the latest one with SLC. But, here are a few aspects you can consider according to your primary operation:

  • SLC for enterprise applications and workstations, since it's the fastest
  • NAND-based drives, i.e., NVME or SATA SSDs with NAND Flash for gaming or work computers
  • MLC for PCs and laptops. However you can also pick SLC storage, but such devices for consumer computers tend to be a tad bit expensive. Reference: look up Gen-4 SSDs.
  • Secure Digital Card, commonly known as SD card for mobile phones, camera devices, etc. All of these have NAND flash memory.

This makes selection a lot easier. However, it's important to know that any NVME devices after Gen 2 are based on 3D NAND, the fastest NAND flash available today. But, currently, Gen 4 SSDs are the fastest and most expensive.

Conclusion

Hope this article was helpful regarding NAND flash memory and the most frequently related queries to it. We explored the few types of NAND flash and how they're all so different, despite being similarly categorized.

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