EEPROM vs NOR Flash vs FRAM: Choosing Non-Volatile Memory by the Job, Not the Buzzword
Choosing non-volatile memory wrong isn’t about “can it work” — it’s being too expensive, too slow, or worn out. Using four axes (erase granularity, read access, write endurance, density/cost), this guide explains EEPROM (byte-write, for settings), NOR Flash (XIP, for code), NAND (bulk), and FRAM (near-unlimited endurance but small and pricey), mapped to FMD FT24C and GigaDevice GD25Q / GD5F.
Four non-volatile memories, four axes
Non-volatile memory (keeps data with the power off) commonly comes in four types: EEPROM, NOR Flash, NAND Flash and FRAM. Choosing wrong isn’t about “can it work” — it’s about being too expensive, too slow, or worn out. The differences come down to four axes: erase granularity (can you change a single byte, or must you erase a whole block), read access (can you read randomly and execute code in place), write endurance and speed, and density and cost. Think the requirement through on these four axes first — most designs really are just “store some settings” plus “store code” — then map to part numbers and you won’t choose wrong.
EEPROM: byte-rewritable small settings
EEPROM’s trait is “byte-readable and byte-writable”: you can change just one byte without erasing a whole block, ideal for frequently, lightly updated settings, calibration parameters, serial numbers and small logs. Endurance is typically ~1 million writes per byte with ~100-year retention; writes are self-timed (a page takes a few milliseconds); interfaces are I²C and SPI. Capacity is small (a few Kbit to ~1Mbit). In the JLink catalog: FMD’s FT24C series is the I²C 24Cxx EEPROM (2Kb–1Mb, Vcc 1.8–5.5V), and FT25C is the SPI-interface sibling. Simply: EEPROM stores “settings.”
NOR vs NAND Flash: code vs bulk data
Though both are called Flash, NOR and NAND are opposite in purpose. NOR Flash can “read randomly, byte by byte,” so it can “execute in place (XIP)” — best for firmware and boot code; but before writing it must “erase a whole sector (e.g. 4KB) / block,” endurance is ~100k cycles per sector, and capacity is moderate (Mb to a few hundred Mb). GigaDevice’s GD25Q is exactly an SPI NOR (single/dual/quad SPI, various densities). NAND Flash is “page-read, page-write, block-erase,” with the highest density (Gb-class and up) and lowest cost per bit, but it must be paired with ECC and bad-block management, suiting bulk data, images, logs and file systems — GigaDevice’s GD5F is SPI NAND (with on-die ECC). In a sentence: NOR stores “code that gets executed,” NAND stores “bulk data / files.”
⚠️ FRAM: near-unlimited endurance, but small and pricey
FRAM (ferroelectric RAM) is a special case: like RAM it can be byte-written at high speed with no erase, writes fast and low-power, and its endurance is virtually unlimited (typically ~10^14 cycles — hundreds of millions of times more writes than EEPROM). Sounds perfect, so why not use it for everything? Because its density is low and cost per bit high — today’s flagship serial FRAM tops out around 16Mbit, far below NOR’s hundreds of Mb and NAND’s Gb-class, and it’s much pricier per bit. So FRAM’s stage is “very frequent writes that must survive power loss, with low power/latency”: data loggers, smart meters, counters, black boxes. An honest note: FRAM is a different memory class on a different supply chain (common sources are Infineon/Cypress, Fujitsu); what the JLink catalog supplies directly is FT24C/FT25C for settings and GD25Q for code — if your application truly needs FRAM-class endurance, we can help evaluate the direction.
How to choose
How to choose, one line each: frequently byte-rewritten small things (settings, calibration, serial numbers) → EEPROM (FMD FT24C / FT25C) — cheap, easy to interface, enough endurance. Code/firmware that gets executed, needing fast random read or XIP → NOR Flash (GigaDevice GD25Q). Bulk data/files at the lowest cost per bit → NAND Flash (GigaDevice GD5F, remember ECC + bad-block management). Very frequent writes that must survive power loss with low power/latency → FRAM (small density, high unit cost, a different supply chain). The rule: erase granularity (byte→EEPROM, sector→NOR, block→NAND) × need XIP (yes→NOR) × write frequency and endurance (very high→FRAM) × capacity and cost (large→NAND). JLink Technology is an authorized FMD and GigaDevice distributor supplying the full range — EEPROM (FT24C/FT25C), SPI NOR (GD25Q) and SPI NAND (GD5F); tell us your capacity, interface, write frequency and endurance needs and we will help with selection and reply with samples, datasheets and pricing.
Products mentioned
FT24C Series I²C EEPROM (2K ~ 256K bit)
The FT24C series are standard I²C serial EEPROMs spanning 2K to 256K bit (FT24C02 ~ FT24C256), compatible with industry-standard pinouts, with a wide 1.8V ~ 5.5V supply — widely used to store configuration parameters, calibration data, and serial numbers.
GD25Q128 128Mbit SPI NOR Flash
The GD25Q128 is a 128Mbit (16MB) serial SPI NOR Flash, 2.7~3.6V supply, up to 133MHz, with Dual/Quad I/O, 4KB sector and 32/64KB block erase, and 256-byte page program. In SOP8 / WSON8 with a standard JEDEC pinout and command set, it is a common second source for the Winbond W25Q128.
GD5F1GQ5 1Gbit SPI NAND Flash
The GD5F1GQ5 is a 1Gbit SPI NAND Flash from GigaDevice with a 2KB page and 128KB block (64 pages), supporting x1/x2/x4 (Quad) SPI. The series splits into on-chip-ECC variants (UE, 2.7~3.6V, up to 133MHz) and ECC-free variants (RE, 1.7~2.0V, 104MHz), in WSON8 — for code and data storage on MCUs/SoCs.
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