BY25Q128ASSIG from BOYAMICRO BY25Q128ASSIG R, in a SOP-8-208mil. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	/CS	input	Chip Select, active-low. Drive low to enable the device and start an SPI transaction; drive high to place the device in Standby and put all outputs into high impedance.
2	SO/IO1	bidirectional	Serial Data Output for Standard SPI (data shifted out on falling edge of SCLK). Becomes bidirectional IO1 during Dual/Quad Instructions.
3	/WP/IO2	bidirectional	Write Protect, active-low, prevents status register writes and hardware-protects memory when SRP1/SRP0 configured accordingly. Has internal pull-up; may be left unconnected if not used. Becomes IO2 in Quad SPI mode.
4	VSS	power_in	Ground reference for the VCC supply.
5	SI/IO0	bidirectional	Serial Data Input for Standard SPI; receives instructions, addresses, and program data latched on the rising edge of SCLK. Becomes bidirectional IO0 during Dual/Quad Instructions.
6	SCLK	input	Serial Clock input providing the synchronization reference for the SPI interface. Instructions, addresses, and input data are latched on the rising edge; output data changes on the falling edge.
7	/HOLD/IO3	bidirectional	Hold, active-low, pauses serial communication with the device without terminating an in-progress write/program/erase. Has internal pull-up; may be left unconnected if not used. Becomes IO3 in Quad-I/O mode.
8	VCC	power_in	Core and I/O power supply. Single 2.7 V to 3.6 V supply used for all read, program, and erase operations. Must remain within VCC(min)-VCC(max) during all operations.

Key specifications

Parameter	Value
Manufacturer	BOYAMICRO BY25Q128ASSIG R
Package	SOP-8-208mil
Category	Memory
Pins	8

Ordering variants

BY25Q128ASSIG
BY25Q128ASSIGPIG
BY25Q128ASSIGPI
BY25Q128ASSIGZSIG
BY25Q128ASSIGZS
BY25Q128ASSIGVSIG
BY25Q128ASSIGVS
BY25Q128ASSIGUSIG
BY25Q128ASSIGUS
BY25Q128ASSIGXSIG
BY25Q128ASSIGXS
BY25Q128ASSIGFSIG
BY25Q128ASSIGFS

CAD (KiCad official)

Symbol: BY25Q128ASSIG
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOP-8-208mil (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`by25q128assig.step`	122 KB	You want the bare part, or you mark your own boards.
`by25q128assig-etched.step`	2.9 MB	You want the part with `BY25Q128ASSIG` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 702 faces against 147 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

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

Datasheet: BOYAMICRO BY25Q128ASSIG R datasheet (77 pp, sha256 65bba7895d2ef403, retrieved 2026-08-17, tier: lcsc)
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