CAT24C256WI-GT3 from onsemi, in a SOIC-8. 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	A0	input	Device address input bit 0. Hard-wired to VCC or VSS to set the least significant bit of the 3-bit I2C slave address, allowing up to eight CAT24C256 devices to share the bus. Internally pulled down to GND with a weak pull-down.
2	A1	input	Device address input bit 1. Tie to VCC or VSS to select part of the 3-bit I2C slave address. Internally pulled down to GND with a weak pull-down.
3	A2	input	Device address input bit 2 (MSB of the address select field). Tie to VCC or VSS to select part of the 3-bit I2C slave address. Internally pulled down to GND with a weak pull-down.
4	VSS	power_in	Ground / 0 V supply reference for the device.
5	SDA	bidirectional	I2C serial data line. Open-drain bidirectional pin used to transfer address and data into and out of the EEPROM; requires an external pull-up resistor to VCC. Input capacitance is 8 pF max.
6	SCL	input	I2C serial clock input. Positive edges clock data into the device; negative edges clock data out. Supports Standard (100 kHz), Fast (400 kHz), and Fast-Plus (1 MHz) modes.
7	WP	input	Write Protect input. When held HIGH, all write operations to the entire memory array are inhibited; when LOW (or left floating with the internal pull-down), writes are enabled. Internally pulled down to GND (strong pull-down until ~0.5 x VCC, then weak).
8	VCC	power_in	Positive supply voltage input. Operating range 1.8 V to 5.5 V. Standby current typically < 2 uA.

Key specifications

Parameter	Value
Manufacturer	onsemi
Package	SOIC-8
Category	Memory
Pins	8

Ordering variants

CAT24C256WI-GT3W
CAT24C256WI-GT3
CAT24C256WI-GT3X
CAT24C256WI-GT3XI
CAT24C256WI-GT3Y
CAT24C256WI-GT3YI
CAT24C256WI-GT3Z
CAT24C256WI-GT3ZI
CAT24C256WI-GT3L
CAT24C256WI-GT3LI
CAT24C256WI-GT3ZD2
CAT24C256WI-GT3HU4

CAD (KiCad official)

Symbol: CAT24C256WI-GT3
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOIC-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`cat24c256wi-gt3.step`	122 KB	You want the bare part, or you mark your own boards.
`cat24c256wi-gt3-etched.step`	2.7 MB	You want the part with `CAT24C256WI-GT3` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 671 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: onsemi datasheet (18 pp, sha256 f6b7e0279c00395b, 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