Comparison of Advantages and Disadvantages: SD NAND vs. eMMC

Recently, we have come into contact with some customers who initially planned to use eMMC but felt that something was not quite right. After conducting in-depth discussions with them, we asked: What kind of eMMC do you really want? Their responses included:

• The smallest eMMC

• The easiest eMMC to solder

• The lowest-capacity eMMC

• The eMMC with the fewest pins

• The lowest-power-consumption eMMC

• The eMMC with the longest erase/write lifespan

• The eMMC using SLC NAND wafers

• The most stable eMMC in terms of performance

After analyzing the customers’ requirements, we found that CS SEMI SD NAND is a better fit for them.

CS SEMI SD NAND is a miniature eMMC, featuring:

• Compact size: 6 × 8 mm

• Optimized cost: Minimum capacity of 128MB, offering cost advantages

• Easy soldering: 8-pin design, making assembly more convenient

• High endurance: Built with SLC NAND wafers, supporting 100,000 erase/write cycles

• Plug-and-play compatibility: Supports SDIO, enabling seamless integration

• Similar architecture to eMMC: Both SD NAND and eMMC consist of an internal NAND Flash wafer, a NAND Flash controller, and firmware, making them closely related.

For more details about CS SEMI SD NAND, please refer to the following link:https://www.longsto.com/product/68-en.html

When customers have the following requirements, choosing SD NAND may be more suitable than eMMC:

1. Need for a smaller chip size:

• Soldered SD card: 6 × 8 mm

• eMMC: 11.5 × 13 mm

To compare their size and packaging, here’s an image of the product (from left to right).






2. Need for small capacity:

• SD NAND: 128MB – 4GB

• eMMC: Capacity ≥ 16GB

3. Need for long endurance and durability:

• SD NAND uses SLC NAND Flash wafer, with an erase/write cycle life of 50,000 to 100,000 cycles

• eMMC uses MLC NAND, with an erase/write cycle life of 3,000 cycles (non-mainstream), or TLC NAND, with an erase/write cycle life of around 500 cycles (mainstream).

4. Need for easy soldering with fewer pins:

• SD NAND: LGA-8 package, easy for both machine and manual placement

• eMMC: 153-ball BGA package, which significantly increases the soldering difficulty

5. The customer's CPU does not support eMMC interface but requires large storage:
   This situation is commonly encountered in MCU platforms. In this case, CS SEMI SD NAND is the perfect choice.

6. Need fewer PCB layers:
   Many customers create products like toys or small appliances where a 2-layer PCB is usually enough. However, using eMMC would require at least a 4-layer PCB, increasing routing difficulty and PCB cost.

When is it more appropriate to use eMMC?

1. Larger capacity requirements:
   When the capacity needed is ≥ 8GB.

2. The main controller supports eMMC:
   The system’s main control unit must have eMMC interface support.

3. Adequate PCB area and more than 4 layers:
   Using eMMC requires enough space on the PCB (11.5 × 13 mm). The PCB must be at least 4 layers, and you will need to use buried/blind vias. Additionally, BGA with 153 balls and a 0.5mm pin pitch is required.

If you have any questions, please contact us

Email：line@longsto.com