SN74CBT3251DBQR from Texas Instruments, in a SSOP-16-150mil. 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	B4	bidirectional	Port B4. One of eight switched I/O ports; connects to A when selected (S2 S1 S0 = 0 1 1) and OE is low.
2	B3	bidirectional	Port B3. Switched I/O port selected when S2 S1 S0 = 0 1 0 and OE is low.
3	B2	bidirectional	Port B2. Switched I/O port selected when S2 S1 S0 = 0 0 1 and OE is low.
4	B1	bidirectional	Port B1. Switched I/O port selected when S2 S1 S0 = 0 0 0 and OE is low.
5	A	bidirectional	Common OUT/IN. Shared terminal of the 1-of-8 FET switch; connects to whichever Bn port is selected by S0/S1/S2 when OE is low.
6	NC	unconnected	No internal connection.
7	OE	input	Output Enable, active low. When low the selected A↔Bn switch is closed; when high all switches are disconnected (high-Z). TTL-compatible input (VIH ≥ 2 V, VIL ≤ 0.8 V).
8	GND	power_in	Ground reference for the device.
9	S2	input	Select bit 2 (MSB) of the 3-bit channel-select input. Together with S1/S0 chooses one of eight B ports (see Table 1). TTL-compatible input.
10	S1	input	Select bit 1 of the 3-bit channel-select input. TTL-compatible input.
11	S0	input	Select bit 0 (LSB) of the 3-bit channel-select input. TTL-compatible input.
12	B8	bidirectional	Port B8. Switched I/O port selected when S2 S1 S0 = 1 1 1 and OE is low.
13	B7	bidirectional	Port B7. Switched I/O port selected when S2 S1 S0 = 1 1 0 and OE is low.
14	B6	bidirectional	Port B6. Switched I/O port selected when S2 S1 S0 = 1 0 1 and OE is low.
15	B5	bidirectional	Port B5. Switched I/O port selected when S2 S1 S0 = 1 0 0 and OE is low.
16	VCC	power_in	Supply voltage input, 4.0-5.5 V recommended (7 V absolute max). Powers the control logic; the FET switches themselves pass signals from 0 V to VCC.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	SSOP-16-150mil
Category	Logic
Pins	16

Ordering variants

Same part, different packaging or reel option.

SN74CBT3251DBQR
SN74CBT3251DBQRD
SN74CBT3251DBQRDR
SN74CBT3251DBQRDBR
SN74CBT3251DBQRPW
SN74CBT3251DBQRPWR
SN74CBT3251DBQRRGY
SN74CBT3251DBQRRGYR

CAD (KiCad official)

Symbol: SN74CBT3251DBQR
Footprint: Package_SO:SSOP-16_5.3x6.2mm_P0.65mm
3D model: SSOP-16-150mil (KiCad packages3D, STEP)

Provenance

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

Datasheet: Texas Instruments datasheet (30 pp, sha256 0284abee7e48eb34, 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