China is now the world leader in high-speed rail track mileage, and the development of rail transit is progressing rapidly. Rail transit equipment is becoming increasingly intelligent, with many electronic devices being added, leading to a growing need for data storage. There are four common types of data frequently encountered:

1. Temperature, speed, and station arrival information inside the carriages.

2. Various sensor information between carriages and stations.

3. Log files.

4. Communication data backups with the backend.

The requirements for storage chips mainly include the following points:

1. High Stability: Rail transit experiences significant vibrations, so the storage device must be vibration-resistant, which rules out products like CF cards or TF cards (external card types).

2. High/Low Temperature Resistance: Most rail transit equipment operates outdoors, and there is a considerable temperature difference between the northern and southern regions of China.

3. Fast Small File Read/Write Speed: Rail transit equipment continuously reads and writes data, but the data size for each operation is relatively small. Therefore, high-speed read/write performance for small files is required. In contrast, there is no high demand for large file read/write speeds, as there is no large volume of audio or video data.

4. Special Encryption Requirements: There may be specific encryption needs for the data.

5. Higher Capacity Than NOR Flash: The required capacity should be at least 32MB or more.

6. Easy to Solder: Most servo devices in rail transit use MCU platforms such as STM32, NXP, and TI. When using eMMC for large-capacity storage on such platforms, several issues arise:

• The platform may not support eMMC.

• eMMC has too many pins, making it difficult to solder.

• The soldering points on eMMC are too small, making it unsuitable for use in rail transit platforms.

The second-generation SD NAND product launched by CS Semiconductor perfectly meets the storage chip requirements for rail transit products:

1. Capacity: Available in 128MB, 512MB, and 4GB sizes, making it easier to optimize costs.

2. Fast Small File Read Speed: The read speed for small files is more than 10 times faster than conventional products. Specific test data can be obtained by contacting us.

3. High/Low Temperature and Thermal Shock Resistance: The CS second-generation SD NAND can withstand high and low temperatures and thermal shock.

4. Standard SDIO Interface: CS SD NAND uses the standard SDIO interface, which is supported by most mainstream MCUs.

5. LGA-8 Package: The CS SD NAND comes in an LGA-8 package, with larger pads that make soldering stable and easy, ensuring reliable soldering quality.

The CS SD NAND has already been successfully applied in CRRC (China Railway Rolling Stock Corporation) equipment.