AT93C66B-SSHM-T from Microchip, 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	CS	input	Chip Select. A rising edge on CS starts a valid instruction; holding CS high maintains sequential-read mode. CS low places the device in standby.
2	SK	input	Serial Data Clock. Synchronizes DI on rising edges and DO transitions. Max frequency 2MHz at 4.5-5.5V, 1MHz at 2.5-5.5V, 250kHz at 1.7-5.5V.
3	DI	input	Serial Data Input. Receives the start bit, opcode, address, and (for WRITE/WRAL) data. Sampled on rising edge of SK.
4	DO	tri_state	Serial Data Output. Clocks out read data on falling edges of SK and reports Ready/Busy status during self-timed program/erase cycles. High-impedance when CS is low or the device is idle. Max output current 5.0mA.
5	GND	power_in	Ground reference (0V) for the device.
6	ORG	input	Internal Organization select. ORG tied to VCC selects the x16 organization (256 words x 16); ORG tied to GND selects the x8 organization (512 words x 8). Has an internal ~1MOhm pull-up so leaving ORG floating defaults to x16.
7	NC	unconnected	No connect. Not internally bonded; may be left floating or tied to any potential within the absolute maximum rating.
8	VCC	power_in	Positive supply, 1.7V to 5.5V. Typical ICC 0.5mA (read/write at 1MHz, 5V), max 2.0mA. Standby current 0.4uA typ @ 1.7V, 10uA typ @ 5V.

Key specifications

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

Ordering variants

AT93C66B-SSHM-TSSHM-B
AT93C66B-SSHM-T
AT93C66B-SSHM-TXHM-B
AT93C66B-SSHM-TXHM-T
AT93C66B-SSHM-TMAHM-T
AT93C66B-SSHM-TMEHM-T
AT93C66B-SSHM-TCUM-T

CAD (KiCad official)

Symbol: AT93C66B-SSHM-T
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
`at93c66b-sshm-t.step`	122 KB	You want the bare part, or you mark your own boards.
`at93c66b-sshm-t-etched.step`	2.9 MB	You want the part with `AT93C66B-SSHM-T` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 708 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: Microchip datasheet (21 pp, sha256 821c552202a268a8, 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