Have you ever wondered how do SD cards work?

In this article, we will delve into the basics of how SD cards work.

We will explore the basics of SD cards, the technology behind it,  how they store and retrieve data and how to use them properly.

We will also discuss some common problems associated with SD cards, such as corruption and write protection, and how to address them.


What is an SD Card

An SD (Secure Digital) card is a common storage device that has tiny size, high memory density, high data transfer rate, and reliable security. It is a form of flash memory that can be written to thousands of times. You do not require power to retain an SD card’s contents. That’s why it’s amongst the top choices for use on different devices – from computers to phones, from cameras to cars, and so on.

In addition, SD cards contain no moving parts, so they are significantly more sturdy and can withstand accidental bumps and falls. However, note that in order to make use of an SD card, your device must be capable of reading cards. At times, some electronic devices like digital cameras and cell phones do contain an SD slot but may be modified to not accept cards. When it comes to computers, a lot of them include memory card slots for SD and other memory cards. If yours doesn’t include it, you can purchase a USB memory card reader to enable your computer to use an SD card.

connect sd card with a mac


How Do SD Cards Work

While most people are familiar with SD cards, not many know about their working principle. So, how do SD cards work in phones and other electronic devices? Here’s the answer.

SD cards use a series of electronic components called NAND chips (a type of flash memory) to store digital files. These chips allow data to be written and stored on the SD card and retain it without a power supply. As these NAND chips have no moving parts, data can be transferred from SD cards quickly. The data transfer speeds that SD cards offer far exceed the speeds you get on many other storage devices, like CDs or hard drives.

When data is written to an SD card, it is first stored in a buffer memory. The data is then written to the appropriate memory cells in blocks of data, which are organized into pages. Each page consists of a certain number of bytes of data plus additional bytes for error correction and other control information.

When data is read from an SD card, the controller reads the data from the appropriate memory cells and sends it to the device that requested the data. The controller may also perform error correction and other operations to ensure the integrity of the data being read.

NAND chips are highly durable and do not wear out easily. So, you can write data on SD cards thousands of times over their lifetime.

Write Protection Feature

Some SD cards come equipped with a “lock” to prevent the accidental loss of data. This is achieved via a small switch, that, if enabled, does not let new data be written or old data be overwritten on the card. You can easily also remove write protection from your SD card.

The write protection switch is typically located on the side of the SD card, near the label or brand name. It can be moved back and forth between the lock and unlock positions. When the switch is in the locked position, the card is write-protected and cannot be written to, modified or formatted until the switch is moved back to the unlock position.

This feature is particularly useful when handling important data or using the SD card as a storage device for critical files. It provides an added layer of protection against accidental deletion or corruption, allowing the user to feel more secure about their data.

write protection feature


How To Use SD Cards

Here’s how you can use SD cards on different electronic devices:

How to Use SD Card on a Computer

Here are the steps to use SD cards on a computer:

  1. Connect the SD card to your computer via the card slot.
  2. Open File Explorer where the SD card is displayed as a drive under Devices and Drives. The drive is usually labeled by its brand name and assigned with a drive letter.
  3. Now, double-click the drive to browse or manage the files on the SD card or transfer data between the SD card and the computer.
  4. Once your work with the SD card is done, safely remove it from your PC by right-clicking the drive and choosing the Eject option. Do not miss this step in order to avoid data loss or SD card corruption.

If your SD card is corrupted check out this article to fix it fast and easy.

How to Use SD Card on a Camera

For an SD card to work properly with your camera, it needs to be formatted before first-time usage. You can format it on a computer (Mac or Windows), but it is preferable that you format it on a camera. This will make it fully compatible with your camera’s file type.

Here are the steps to use SD cards on a camera:

  1. Turn off your camera and gently insert the SD card into the card slot.
  2. Turn on your camera and choose an option like Menu or Preferences.
  3. Find and select the Format
  4. Confirm to format the SD card and then wait for the process to finish.

Once the process finishes, you can start using the camera, and store your favorite shots on your SD card.

How to Use SD Card on a Phone

Today, not many smartphones come with SD card slots, as phone manufacturers have significantly bumped up the internal memory of their devices. Therefore, SD cards on smartphones are not widely used nowadays.

However, if you have an old phone with a card tray, it’s pretty straightforward to use an SD card on it. Just insert your SD card in the SD card slot, set it up with the on-screen instructions, and you’re good to go! In some phones, you can even use your SD card as internal storage (on Android).


How Many GB Should My SD Card Be?

The amount of GBs you should choose for your SD card depends on the resolution, frame rate, and bitrate of the videos you will be recording. Generally, for video cameras that shoot in 1080p or Full HD, a 32GB or 64GB SD card should suffice. However, if you plan to shoot in 4K resolution or higher, it is recommended to use a larger capacity SD card, such as 128GB or even 256GB, to accommodate the larger file sizes.

It’s also important to consider the bitrate of your video recording, as higher bitrates result in larger file sizes. For example, a 1080p video recorded at 60fps with a high bitrate may require a larger capacity SD card than a 1080p video recorded at 30fps with a lower bitrate. As a general rule of thumb, it’s better to choose a larger capacity SD card than necessary to ensure you have enough storage space for your videos.



Thanks for reading!

I hope this guide helped you gain all the information about how SD cards work 🙂 


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