Since their introduction in the 1990s, memory cards have remained among the most successful, trusted and low-cost storage solutions available. Consumer memory cards are cheap and commonly used to store images, videos, audio and text in portable devices such as cameras and smartphones. However, they are often also deployed for industrial applications that they are just not designed for.
Industrial-grade memory cards incorporate tough, reliable and high-quality components that can perform reliably over long periods of time to ensure maximum availability, minimal downtime and better return on investment. Industrial requirements are vastly different from personal or consumer use, being often not only mission critical but also safety and life critical. As more industrial systems become autonomous or require little to no human intervention, the efficiency of data storage and the timely access, delivery and analysis of information have never been more crucial.
Basing a decision on card capacity is a common mistake. For instance, believing that a “32GB card will be plenty of storage for our application”. SD cards have different modes, such as High Capacity (HD) and eXtended Capacity (XC), and may not work in every application, so it’s worth checking card compatibility from the outset.
Ideally, customers in the industrial sector should make purchasing decisions based on the total cost of a solution rather than immediate, short-term costs. Total cost of ownership may seem trivial for an SD or microSD card but when we factor in downtime of kit, engineering resource, logistics and human resource, not to mention customer dissatisfaction and any knock-on effects, it really is important to make the right decision from the design stage.
So, how do you choose the right storage solution for industrial applications?
Key considerations include (but are not limited to) reliability, endurance, data integrity, capacity, speed and compatibility. It may sound confusing, but by understanding what the cards are being used for and how much data is being written to them, the right solution can be found. An additional advantage of industrial-grade cards is that they are highly customisable and can be tweaked specifically for your application, for example to prolong card lifespan or use less power.
It’s what’s inside that counts
When an SD card is opened (image 1 below) to reveal its inner workings, it will look fundamentally the same whether a consumer or industrial card. However, some manufacturers such as ATP offer SiP (System in Packaging, image 2) which completely encapsulates all contacts and components. Both cards will have a NAND Flash chip (the large block) and both will have a controller (the small block). The NAND Flash is where everything is stored; data files, presentations, music, pictures and so on. The controller is the brains of the device – it’s the part that communicates with the host device and manages the flash file system directory. The controller is also responsible for wear levelling, error correction and garbage collection so it’s vital in making the cards work. Industrial grade cards can typically operate in temperatures of between -40°C to 85°C which is also known as wide temperature. Consumer cards typically can operate between -25°C to 85°C. So as you can see for applications that need to run in harsh environments for long periods of time industrial grade makes perfect sense.
Different types of NAND flash
With different types of NAND flash it is important that you chose the right one for your application. The table below, gives a brief outline of the characteristics for the different types of NAND Flash found in SD and microSD cards
3D NAND Flash impact
Frequently, when we see cards failing it is because the wrong type of NAND flash within the card is being used. NAND flash comes in numerous grades, each with very different performance and endurance specifications, so it’s worth finding out how the NAND used could impact the card performance. Expert advice will help to ensure that the application works right first time.
3D NAND flash is now firmly established in consumer devices but industrial-grade 3D NAND has only recently become available. So, where does that leave SLC, MLC and pSLC – the established types of NAND flash? The answer is, nothing really changes. As mentioned earlier the performance and endurance of NAND flash varies from type to type. SLC sits at the top, being the fastest, most durable (and expensive) but it plays a vital role in the industrial sector. NAND manufacturers are not going to stop making this established flash as demand is still strong and supply plentiful, so, for those projects that need to run for years and require a stable industrial flash supply need not worry.