Comparison between CS SD NAND and SPI NAND
Previously, we have articles about the comparison between CS SD NAND and eMMC, TF card, Raw NAND and other flash products. Now we will talk about the comparison between CS SD NAND and SPI NAND.
The two products are similar in outlooking. They have the same 6*8mm size, same assemble technology: LGA-8. The both products use SLC NAND Flash internally. The erasable life can reach 5-10W times.
But what about their differences.
Interfaces are different.
SD NAND is normally connected to SDIO. Some platforms also support SD NAND to SPI interface (but the read and write speed may be slower); SPI NAND is connected to SPI interface, but can’t support SDIO.
Drivers are different.
Basically, mainstream CPU platforms have their own SDIO drivers, so SD NAND does not require users to write additional drivers; In addition, SD NAND has the built-in flash controller which can manage bad block, Wear-Leveling Algorithm, dynamic and static EDC/ECC algorithms and so on. In other words, the management for NAND Flash is enough and complete. SPI NAND is mainly used for protocol conversion from parallel port to SPI interface. Some manufacturers have built-in EDC/ECC algorithm, but other management mechanisms are not included. This causes users to write drivers when using SPI NAND.
R/W speed is different.
Due to the difference between interfaces and protocols of the two products, the speed difference between them is large. SD NAND uses 4-bit transmission bandwidth. Compared with SPI NAND, the read/write speed is much faster. The maximum write speed can reach Class 10; While SPI NAND is still adopt 1-bit transmission mode, the read and write speed is much slower.
Stability is different.
SD NAND is much better in stability due to its built-in management algorithms, especially for power failure protection. CS SD NAND II passed the customer's 10K random power down tests. But both SPI NAND and Raw NAND are easy to lose data when the power is suddenly off when writing data.
Generally, SD NAND is a total solution which complete the NAND Flash algorithm, while SPI NAND mainly finish the protocol conversion, and the built-in algorithm is not complete.
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