Tips for Choosing the Best SD Card for Your Application
A common question we hear from customers at Delkin is, “Which SD card is the best?” It is a reasonable question; unfortunately, the answer isn’t straightforward. Every host application is different, and there isn’t a single SD card that is the best fit for every application. As such, our team needs to understand more about your device and how it is used before we can make a recommendation.
That is why our Customer Applications team works so closely with each customer individually. We take the time to understand their specific application and needs before recommending an SD card that will be the best fit for them in terms of operations and budget. We’ve helped a long list of customers meet their needs for SD cards for industrial applications, even finding solutions for challenging cases.
This commitment is demonstrated by this story of how we helped one of our customers find the best SD card for their industrial application that was not write-intensive. The customer was not sure of the file sizes that would be written or how often write operations would happen. They were also unsure of the operating temperature.
The application itself was industrial. However, the company was considering a different grade of SD card because of the low write demands and the lack of information about operating temperature. They reached out to Delkin to see if the TLC SD card they were considering would be a good choice. Delkin had a suspicion that another card could be a better option. Our team got to work helping the customer find the right solution for their application.
The customer in question approached Delkin after becoming frustrated with the experience they were having with qualification testing for the TLC SD cards they were planning to use. Every single SD card they attempted to qualify in their device had failed thus far. As a result of all of the failed tests, their launch timeline was behind. Plus, they were dealing with climbing costs caused by the delays. Even worse, the customer was becoming worried that perhaps the issue wasn’t with the SD cards, but with their application instead.
After listening to the customer’s story, Delkin decided to examine the host application usage model during qualification to find the core of the problem. In order to achieve this, Delkin advised the customer to perform repeated write operations in operating conditions of 85 degrees C to see how the application and the SD card would react. This process provided multiple clues to the Delkin team.
After reviewing the SMART data from the cards’ qualification testing process, Delkin noticed a clear issue. The program and erase cycles that were being attempted during the testing were more than the TLC SD cards could handle. The customer knew that their application wouldn’t be used for write-intensive tasks, but they didn’t know the size of the files that would be written. As it turns out, they were writing 9 TB of data during the testing. The overload, coupled with the extreme operating temperature, left the cards only capable of performing read operations.
The Utility SD cards that Delkin considered for the customer featured MLC (multi-level cell) Industrial 3D Flash. With MLC Industiral 3D Flash, additional data are stored per cell. This kind of memory is used in both commercial and industrial applications. It is faster than TLC flash memory. When it is rated as Utility, it typically has features that are associated with industrial-grade memory, like the ability to withstand extended temperature ranges, and is more appropriate for industrial applications.
However, the gold standard for industrial flash memory is single-level cell, or SLC, flash. Only one bit of data is stored per cell with this kind of flash memory. This makes it the fastest, most reliable, and most secure version of flash available. This kind of flash memory is especially suited to the extreme operating conditions many industrial applications experience. In some cases, industrial designers opt for MLC Utility cards over SLC when they need high-capacity storage; however, that wasn’t the case for this customer.
After additional testing and working with the customer to understand their needs, Delkin’s team ultimately decided that a low-capacity SLC SD card would be the best solution. With this kind of SD card, the customer would get a high level of reliability. As a result, they could get back on track with their launch date with confidence. The team also taught the customer how to read the SMART data from the card; this would let them know if any issues were happening with their card that could lead to the application failing in the field. The customer was thrilled that they had found a way to get their application ready for launch.
It’s common for applications to rely on NAND flash memory, but not all flash memory is created the same. An industrial SD card is almost always the best solution for industrial applications, rather than memory that was designed with the consumer or commercial market in mind. In addition, OEMs should look for flash memory suppliers who can provide customization and assist in the testing process.
Lean on Delkin’s Technical Team
Get customized support for your host application today. Delkin’s Customer Applications team is available to help with your unique application needs and be your true partner in the industrial flash storage qualification process.
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