SN74CB3Q3257PWR from Texas Instruments, in a TSSOP-16. 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	S	input	Channel select input. Selects which B port (B1 or B2) is connected to the common A port on each of the four channels. TTL/CMOS-compatible; drivable by 5V or 3.3V logic.
2	1B1	bidirectional	Channel 1 I/O 1. B-side port of channel 1, connected to 1A when S selects the B1 leg and OE is low. Supports 0-5V signaling; ron ≈ 4Ω typ.
3	1B2	bidirectional	Channel 1 I/O 2. B-side port of channel 1, connected to 1A when S selects the B2 leg and OE is low. Supports 0-5V signaling; ron ≈ 4Ω typ.
4	1A	bidirectional	Channel 1 common (A) port. Connects to either 1B1 or 1B2 through the FET switch as selected by S, when OE is low.
5	2B1	bidirectional	Channel 2 I/O 1. B-side port of channel 2, connected to 2A when S selects the B1 leg and OE is low.
6	2B2	bidirectional	Channel 2 I/O 2. B-side port of channel 2, connected to 2A when S selects the B2 leg and OE is low.
7	2A	bidirectional	Channel 2 common (A) port. Connects to either 2B1 or 2B2 through the FET switch as selected by S, when OE is low.
8	GND	power_in	Ground reference. 0V return for the device.
9	3A	bidirectional	Channel 3 common (A) port. Connects to either 3B1 or 3B2 through the FET switch as selected by S, when OE is low.
10	3B2	bidirectional	Channel 3 I/O 2. B-side port of channel 3, connected to 3A when S selects the B2 leg and OE is low.
11	3B1	bidirectional	Channel 3 I/O 1. B-side port of channel 3, connected to 3A when S selects the B1 leg and OE is low.
12	4A	bidirectional	Channel 4 common (A) port. Connects to either 4B1 or 4B2 through the FET switch as selected by S, when OE is low.
13	4B2	bidirectional	Channel 4 I/O 2. B-side port of channel 4, connected to 4A when S selects the B2 leg and OE is low.
14	4B1	bidirectional	Channel 4 I/O 1. B-side port of channel 4, connected to 4A when S selects the B1 leg and OE is low.
15	OE	input	Output Enable, active low. When low, the selected FET switches are ON connecting A to B1 or B2 per S. When high, all switches are OFF (high impedance).
16	VCC	power_in	Supply voltage input. Recommended operating range 2.3V to 3.6V (absolute max 4.6V). Bypass with a local 0.1µF ceramic capacitor to GND.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	TSSOP-16
Category	Interface
Pins	16

Ordering variants

Same part, different packaging or reel option.

SN74CB3Q3257PWR
SN74CB3Q3257PWRDGV
SN74CB3Q3257PWRDBQ
SN74CB3Q3257PWRRGY
SN74CB3Q3257PWRDYY

CAD (KiCad official)

Symbol: SN74CB3Q3257PWR
Footprint: Package_SO:TSSOP-16_4.4x5mm_P0.65mm
3D model: TSSOP-16 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`sn74cb3q3257pwr.step`	205 KB	You want the bare part, or you mark your own boards.
`sn74cb3q3257pwr-etched.step`	3.4 MB	You want the part with `SN74CB3Q3257PWR` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 840 faces against 255 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: Texas Instruments datasheet (30 pp, sha256 783754d51a8b8d05, 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