How does SD card work? And their Different Classes Explained.

Basically, there is a lot of things you need to know before buying an SD card. Having a lot of varieties, it depends upon you that which one is more suitable for you. So let’s have a look at the type of SD cards (memory Card) which are normally found in the market around us.

Also see this:-How do Hard Drive Works?

Type of SD card (Size Variants)

• Standard SD cards: SD (SDSC), SDHC, SDXC, SDIO — 32 x 24 x 2.1-1.4mm
• miniSD cards: miniSD, miniSDHC, miniSDIO — 21.5 x 20 x 1.4mm
• microSD cards: microSD, microSDHC, microSDXC — 15 x 11 x 1mm

This wide range of Varieties available in SD Card is widely used in a different type of Devices from Smartphone to drones, DSLR Camera to Storage Devices, etc. Depending on the Size they all serve a different purpose.

Storage Space and Data Transfer Speed.

As we have seen the Size Arability of different SD Cards now we Can take a look at the speed and storage space provided by different SD cards.

In 2005 the SD association had made the final approval regarding the microSD card which has mere support of 128 MB of storage. After that SDHC and SDXC were introduced.

These are the storage capacity and Transfer speed of different type of SD Cards.

• microSD: Max storage of 4GB, the transfer rate of 25MB/s — uses FAT12, FAT16 or FAT16B file systems
• microSD HC: 4GB to 32GB of storage, transfer rates from 50MB/s — typically use FAT32
• micro SD XC: 32GB to 2TB of storage, transfer rates from 50MB/s — uses exFAT

microSD cards were having a Max storage capacity of 24GB. After that, new technology arrived through which we were able to extend the capacity of SD Card from 2 GB to 32 GB and we named it as SDHC (SD High Capacity).

After that due to increase requirement in storage space a new SD Card was launched which was named as SDXC (SD Extended Capacity) Through which we are able to make a card from 32 GB to 2TB

That is not all we need to know about SD Cards there is one more thing which is also important to know before you purchase an SD card for your Device.

Classes in SD Card.

The class of an SD card Shows us the speed of Data transfer supported by the SD Card. For example, if a card is of class 10 than it supports the data transfer speed of 10 Mb/Second. Let’s have a look at where you can find the class of an SD card.

Here is A table where you can Find the class of the following SD Cards

Speed Class	Min. Seq. Writes	UHS Speed Class	Video Speed Class	Ideal Workload
Class 2 (C2)	2MB/s			SD recording and playback
Class 4 (C4)	4MB/s			720p/1080p video
Class 6 (C6)	6MB/s		Video Class 6 (V6)	720p/1080p, some 4K video
Class 10 (C10)	10MB/s	UHS Class 1 (U1)	Video Class 10 (V10)	720p/1080p/4K video
	30MB/s	UHS Class 3 (U3)	Video Class 30 (V30)	1080p/4K video @ 60/120fps
	60MB/s		Video Class 60 (V60)	8K video @ 60/120fps
	90MB/s		Video Class 90 (V90)	8K video @ 60/120fps

Application Performance Class

Excluded from the first table above, there is a relatively new “Application Class” for SD cards — Class 1 and 2 (A1, A2) — which outline minimum IOP performance. A1 cards are good for a random read performance of 1500 IOPS and random writes of 500 IOPS, while A2 steps that up to 4000 IOPS and 2000 IOPS.

Additionally, if you see an SD card stamped with either A1 or A2, you can rest assured that it offers sustained sequential write speed of at least 10MB/s.

Class	Min. Seq. Writes	Min. Random Read	Min. Random Write	Ideal Workload
A1	10MB/s	1500 IOPS	500 IOPS	Editing and updating app data, not just storage
A2	10MB/s	4000 IOPS	2000 IOPS	Higher performance, special uses

Which Card to Buy for Your Particular Requirement.

Well If you want to store some images, videos or other sort of data than it is preferable to use a class 4 or above card.

If you want to record some sort of media than it is recommended that you should buy a card of class 6 for a better video rendering and storage.

If you want to Store your apps in a SD Card than it is recommended to have a card of class 10 which would help your app to load and run on you mobile smoothly.

If you want to record a 4K video in your device than it is recommended that you should use a card of UHS 1 or above as it supports the Fps (Frame Per Second) of a 4K videos.

As of now emerging technology with the joint effort of SD association and PCI-SIG are working on a SD card which would be compatible for PCIe and will provide a speed of 985MB/s. This NVMe Solid State drive would bring a lot of change in the capacity and storage of data.

Best High-Performance micro SD Card

• For Smartphones/Tablet use: SanDisk Extreme 128GB U3/V30 A2 
• For Cameras/Video recording: Delkin 1900x 64GB UHS-II U3/V60
•  Value alternative: Samsung Evo Select 128GB U3