Longsys Embedded Storage Selection Guide
Understanding Embedded Storage Interfaces
embedded storage interfaces have evolved significantly over the years. eMMC (embedded MultiMediaCard) has been the standard for many years, with eMMC 5.1 offering sequential read speeds up to 400MB/s using the HS400 mode. UFS (Universal Flash Storage) is the next generation, with UFS 2.1 offering up to 900MB/s and UFS 3.1 reaching 2100MB/s. The key difference is that eMMC uses a parallel interface while UFS uses a serial M-PHY interface with full-duplex communication. For applications requiring high performance, UFS is the clear choice. For cost-sensitive applications, eMMC continues to offer excellent value.
Capacity Planning Guidelines
capacity planning should consider current requirements plus 2-3 years of growth. For mobile devices, factor in OS size, application storage, user data, and media. A typical Android smartphone requires 16-20GB for the OS, plus space for apps and user data. For automotive infotainment, consider navigation map size (5-15GB), media storage, and application requirements. Industrial systems typically require less capacity but should account for data logging and firmware updates. Always include 20-30% headroom to prevent performance degradation as the drive fills up.
Endurance Calculation Methodology
storage endurance is measured in TBW (Terabytes Written) or P/E (Program/Erase) cycles. To calculate required endurance: 1) Estimate daily write volume (GB/day), 2) Multiply by required lifespan (years), 3) Add safety margin (typically 2x). For example, a system writing 10GB/day for 5 years requires 10 × 365 × 5 = 18.25TB total writes. With 2x safety margin, select storage with 36.5TBW or higher. Consumer TLC NAND typically offers 100-300 TBW per 128GB, while pSLC mode can provide 10x improvement. Contact LiTong FAEs for application-specific endurance analysis.
Temperature Range Selection
operating temperature range is critical for reliability. Consumer-grade (0°C to 70°C) is suitable for typical consumer electronics. Industrial-grade (-40°C to +85°C) is required for factory automation, outdoor equipment, and harsh environments. Automotive-grade (-40°C to +105°C or +125°C) is required for automotive applications. Wide temperature range products undergo additional screening and testing, resulting in higher cost but significantly improved reliability. Always verify the actual operating environment including worst-case conditions before selecting temperature grade.
💡 FAE Insights
📋 Customer Cases
Smartphone OEM
Challenge
Needed to balance performance and cost for mid-range device
Solution
Selected 128GB UFS 2.2 based on performance requirements and cost targets
Customer Feedback
"Achieved target boot time under 20 seconds while maintaining competitive BOM cost"
Industrial Equipment Manufacturer
Challenge
Required reliable storage for 24/7 operation in factory environment
Solution
Selected industrial eMMC with pSLC mode for enhanced endurance
Customer Feedback
"System operational for 3+ years with zero storage-related failures"
Frequently Asked Questions
1. When should I choose UFS over eMMC?
Choose UFS when your application requires: 1) Sequential read speeds above 400MB/s, 2) Fast app launch times (flagship smartphones), 3) High-resolution video recording (4K/8K), 4) Large file transfers, or 5) Gaming applications with large assets. UFS 3.1 provides up to 2100MB/s sequential read compared to 400MB/s for eMMC 5.1. However, UFS comes at higher cost and complexity. For applications where eMMC performance is sufficient, it remains the cost-effective choice.
2. How do I calculate the right capacity for my application?
Calculate capacity requirements by summing: 1) OS and firmware size, 2) Application storage requirements, 3) User data and content storage, 4) Temporary and cache space, 5) Future growth margin (20-30%). For example, an automotive infotainment system might need: OS (16GB) + Apps (8GB) + Maps (10GB) + Media (20GB) + Cache (10GB) + Growth (20%) = 78GB → Select 128GB. Always round up to the next standard capacity and include headroom for optimal performance and longevity.
3. What is pSLC mode and when should I use it?
pSLC (pseudo-SLC) mode configures TLC NAND to store 1 bit per cell instead of 3 bits, significantly improving endurance (10x) and performance while reducing capacity to 1/3. Use pSLC mode for: 1) High-write applications (data logging), 2) Industrial systems requiring maximum reliability, 3) Boot partitions in automotive systems, 4) Applications where endurance is more critical than capacity. The trade-off is higher cost per GB, but for mission-critical applications, the reliability improvement is worth the investment.
4. How does temperature affect storage performance and reliability?
Temperature significantly impacts NAND flash performance and endurance. At high temperatures (>70°C), data retention decreases and error rates increase. At low temperatures (<0°C), program/erase operations slow down. Industrial and automotive-grade products are screened for operation across wider temperature ranges and include enhanced error correction. For reliable operation, maintain case temperature below 70°C when possible. Implement thermal management in high-temperature environments. Wide temperature range products include additional margin for reliable operation at temperature extremes.
5. Where can I find additional resources for Longsys Embedded Storage Selection Guide?
Additional resources for Longsys Embedded Storage Selection Guide are available on the LiTong website including application notes, reference designs, and video tutorials. Contact our FAE team for personalized guidance and access to exclusive technical resources.