W25Q128JV vs 24LC256: Flash or EEPROM for Your Design?
2026-10-10 · PartVane Electronics
Both the Winbond W25Q128JVSIQ and the Microchip 24LC256-I/P keep data when power is off, but they solve different problems. One is a 128 Mbit SPI NOR flash for firmware and bulk data; the other is a 256 Kbit I2C EEPROM for settings and counters. This comparison uses only the Winbond W25Q128JV datasheet (Revision M) and the Microchip 24AA256/24LC256/24FC256 datasheet (DS20001203W).
Key differences from the datasheets
| Item | W25Q128JV | 24LC256 |
|---|---|---|
| Type | Serial NOR flash | Serial EEPROM |
| Density | 128 Mbit (16 MB) | 256 Kbit (32K x 8) |
| Interface | Standard, Dual and Quad SPI | 2-wire I2C |
| Max clock | 133 MHz (266/532 MHz equivalent in Dual/Quad) | 400 kHz (2.5 V to 5.5 V) |
| Supply | 2.7 V to 3.6 V | 2.5 V to 5.5 V |
| Write unit | Program 1 to 256 bytes per page; erase by 4 KB sector, 32/64 KB block or whole chip | Page write up to 64 bytes, self-timed |
| Write time | Page program 0.4 ms typ, 3 ms max; sector erase 45 ms typ, 400 ms max | Page write 5 ms max |
| Endurance | Min. 100K program-erase cycles per sector | More than 1 million erase/write cycles |
| Data retention | More than 20 years | More than 200 years |
| Low-power figures | Power-down under 1 µA (typ.) | Standby 1 µA max (I-temp.), write current 3 mA max |
| Temperature | -40 °C to +85 °C; a -40 °C to +105 °C option is listed | Industrial -40 °C to +85 °C; Extended -40 °C to +125 °C |
| Packages (datasheet) | SOIC 208-mil, SOIC 300-mil (16-pin), WSON, TFBGA, WLCSP | PDIP, SOIC, SOIJ, MSOP, TSSOP, DFN/TDFN, CSP |
Capacity and speed: flash is in another league
16 MB is 512 times the 32 KB of the 24LC256. The W25Q128JV also supports Quad SPI and continuous read for execute-in-place (XIP) use, so a microcontroller can run code or stream assets straight from it. An I2C EEPROM at 400 kHz is not meant for that.
Writing: EEPROM is simpler, flash is cheaper per byte to scale
The 24LC256 takes a page of up to 64 bytes and finishes the write on its own within 5 ms; you do not erase first. The W25Q128JV is organised for erase-then-program: a sector is erased in 4 KB units, then programmed in pages of up to 256 bytes. That means you need a little driver logic (write enable, busy polling), but large data moves quickly.
Endurance: pick by how often you write
For a value that changes often, such as a boot counter, calibration constant or user setting, the 24LC256 specifies more than one million erase/write cycles. The W25Q128JV guarantees a minimum of 100K program-erase cycles per sector, which suits firmware images, logs that rotate across sectors, fonts and lookup tables.
Supply voltage and wiring
The 24LC256 runs from 2.5 V to 5.5 V, so it works on both 3.3 V and 5 V boards. The W25Q128JV needs a 2.7 V to 3.6 V supply, so on a 5 V system plan for level shifting. I2C needs two lines (SDA, SCL) and up to eight 24LC256 devices can share a bus using the A0 to A2 address pins. The flash uses CLK, /CS, DI and DO (plus IO2 and IO3 in Quad mode) and has a /WP pin; the EEPROM has a hardware write-protect pin as well.
Which one should you choose?
- Choose the W25Q128JV for firmware storage, OTA images, display assets, audio, data logging or anything beyond a few kilobytes.
- Choose the 24LC256 for configuration data, serial numbers, calibration values and small counters that are rewritten often.
- Use both when a design needs bulk storage plus a small, frequently updated settings area.
For a smaller flash in the same family, see the W25Q64JVSSIQ (64 Mbit). Need either part? Check the part pages for W25Q128JVSIQ and 24LC256-I/P, then send an RFQ with your quantity and package.
Sources
- Winbond W25Q128JV datasheet, Revision M (Dec 24, 2024): https://www.winbond.com/resource-files/W25Q128JV%20RevM%2012242024%20Plus.pdf
- Microchip 24AA256/24LC256/24FC256 datasheet DS20001203W: https://ww1.microchip.com/downloads/en/DeviceDoc/24AA256-24LC256-24FC256-Data-Sheet-20001203W.pdf