A 128 Mbit (16 MB) serial NOR flash from the Winbond W25Q family, in the wide SOIC-8, the go-to external storage for firmware, fonts, logs, and file systems. It speaks Standard, Dual, and Quad SPI plus QPI, clocking to 104 MHz (up to a 416 MHz-equivalent throughput in Quad), and organizes the array in uniform 4 KB sectors for fine-grained erase. The six SPI pins (CS, CLK, DI/IO0, DO/IO1, WP/IO2, HOLD/IO3) double as the four data lines in Quad mode. Runs from a single 2.7-3.6 V supply.

Pinout

Pin	Name	Type	Function
1	/CS	input	Chip Select input (active LOW). Enables the device for SPI/QPI transactions; when HIGH, DO/IO pins are high-impedance and the device is deselected.
2	DO (IO1)	bidirectional	Serial Data Output in Standard SPI (MISO). Bidirectional IO1 in Dual/Quad SPI and QPI modes carrying data in both directions on shared bus lines.
3	/WP (IO2)	bidirectional	Write Protect input (active LOW) in Standard/Dual SPI - protects the Status Register from being written. Reused as IO2 in Quad SPI/QPI modes when Quad Enable (QE) bit is set.
4	GND	power_in	Ground reference (0V).
5	DI (IO0)	bidirectional	Serial Data Input in Standard SPI (MOSI) - clocked in on CLK rising edge. Bidirectional IO0 in Dual/Quad SPI and QPI modes.
6	CLK	input	Serial Clock input. Provides the timing for serial input and output; up to 104MHz operation.
7	/HOLD or /RESET (IO3)	bidirectional	Hold input (active LOW) pauses serial communication without deselecting the device, or Reset input (active LOW) depending on Status Register HOLD/RST bit. Reused as IO3 in Quad SPI/QPI modes when QE=1.
8	VCC	power_in	Power supply, 2.7V to 3.6V. Active current typically 4mA; power-down current <1uA.

Key specifications

Parameter	Value
Type	Serial NOR flash memory
Density	128 Mbit (16 MB)
Interface	Standard / Dual / Quad SPI + QPI
Max clock	104 MHz (416 MHz equiv. Quad)
Erase granularity	4 KB sector (uniform)
Endurance	100k erase/program cycles
Supply voltage	2.7-3.6 V
Package	SOIC-8 (208 mil)

Ordering variants

Same part, different packaging or reel option.

W25Q128FVSIG (SOIC-8, 208 mil)
W25Q128FVSSIG (SOIC-8)

CAD (KiCad official)

Symbol: Memory_Flash:W25Q128JVS
Footprint: Package_SO:SOIC-8_5.3x5.3mm_P1.27mm
3D model: SOIC-8 208 mil (KiCad packages3D)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Winbond datasheet (100 pp, sha256 c545e2594435d1a1, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF