74HC257D from Nexperia, in a SOIC-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	Common data select input. Selects between the nI0 inputs (S=LOW) and nI1 inputs (S=HIGH) routed to the nY outputs.
2	1I0	input	Data input from source 0 for multiplexer channel 1. Routed to 1Y when S=LOW and OE=LOW.
3	1I1	input	Data input from source 1 for multiplexer channel 1. Routed to 1Y when S=HIGH and OE=LOW.
4	1Y	tri_state	3-state multiplexer output for channel 1. High-impedance when OE=HIGH.
5	2I0	input	Data input from source 0 for multiplexer channel 2. Routed to 2Y when S=LOW and OE=LOW.
6	2I1	input	Data input from source 1 for multiplexer channel 2. Routed to 2Y when S=HIGH and OE=LOW.
7	2Y	tri_state	3-state multiplexer output for channel 2. High-impedance when OE=HIGH.
8	GND	power_in	Ground (0 V) reference.
9	3Y	tri_state	3-state multiplexer output for channel 3. High-impedance when OE=HIGH.
10	3I1	input	Data input from source 1 for multiplexer channel 3. Routed to 3Y when S=HIGH and OE=LOW.
11	3I0	input	Data input from source 0 for multiplexer channel 3. Routed to 3Y when S=LOW and OE=LOW.
12	4Y	tri_state	3-state multiplexer output for channel 4. High-impedance when OE=HIGH.
13	4I1	input	Data input from source 1 for multiplexer channel 4. Routed to 4Y when S=HIGH and OE=LOW.
14	4I0	input	Data input from source 0 for multiplexer channel 4. Routed to 4Y when S=LOW and OE=LOW.
15	OE	input	3-state output enable input, active LOW. When OE=HIGH, all nY outputs are in the high-impedance OFF-state.
16	VCC	power_in	Supply voltage. 2.0 V to 6.0 V for 74HC257; 4.5 V to 5.5 V for 74HCT257.

Key specifications

Parameter	Value
Manufacturer	Nexperia
Package	SOIC-16
Category	Logic
Pins	16

Ordering variants

Same part, different packaging or reel option.

74HC257DD
74HC257DPW

CAD (KiCad official)

Symbol: 74HC257D
Footprint: Package_SO:SOIC-16_3.9x9.9mm_P1.27mm
3D model: SOIC-16 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Nexperia datasheet (15 pp, sha256 9a5ab16a50053e88, 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