RESOURCES
Resources for Memory Selection
Practical notes to help frame your next design discussion.
eMMC or UFS? Start with your host interface. →
Temperature ratings: read the conditions, not just the range. →
eMMC or UFS? Start with Your Host Interface
The first question is what your processor and software support. eMMC and UFS are different interfaces; matching package dimensions does not make one a drop-in replacement for the other.
Next, define the workload: startup, application loading, update size and write behavior. Compare the exact device configuration and the conditions behind any performance figures. A product-family headline is not a system-level benchmark.
Finally, review operating conditions and integration requirements. The listed commercial eMMC and UFS devices specify −25°C to +85°C operation, while selected eMMC families provide wider temperature options.
Bring your SoC, interface, capacity and workload to the selection discussion.
Temperature Ratings: Read the Conditions, Not Just the Range
Operating temperature and storage temperature describe different conditions. Do not use the storage rating to infer what a powered device can support.
The temperature reference also matters. The supplied LPDDR4X specifications use case temperature and identify different conditions for standard and elevated operation. At elevated temperatures, refresh requirements and timing derating need attention.
Selected eMMC devices specify −40°C to +105°C operation. That number alone does not establish automotive qualification. Match the exact device specification and qualification evidence to your system requirements.
When requesting a recommendation, include the temperature range, how it is measured, the workload and the applicable validation requirements.
SPI NAND Capacity: Gb Is Not GB
Lowercase “b” means bits. Uppercase “B” means bytes. Eight bits make one byte.
The 1Gb SPI NAND devices listed here contain a nominal main array equivalent to 128 MiB. The 2Gb and 4Gb options correspond to 256 MiB and 512 MiB respectively. They are not 1GB, 2GB and 4GB devices.
Spare areas, bad blocks, metadata and the software storage layout affect usable capacity. Treat the nominal main-array size as the starting point, then check how your host and software manage the device.
Also verify supply voltage: a 1.8V family is not interchangeable with a 3.3V family without reviewing the complete design.
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Tell us your interface, capacity, operating environment and expected volumes.