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SN74HC251DR

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by Ray

Texas Instruments Signal Switches / Encoders & Decoders / Multiplexers, SOIC-16. Datasheet-verified pinout, KiCad symbol/footprint/3D.

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Contents

README

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SN74HC251DR

Texas Instruments · Signal Switches / Encoders & Decoders / Multiplexers · SOIC-16

SN74HC251DR from Texas Instruments, 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 D3 input Data input 3. Selected when C=L, B=H, A=H. Passed to Y (true) and W (inverted) when OE is low.
2 D2 input Data input 2. Selected when C=L, B=H, A=L.
3 D1 input Data input 1. Selected when C=L, B=L, A=H.
4 D0 input Data input 0. Selected when C=L, B=L, A=L.
5 Y tri_state True (non-inverted) 3-state data output. Drives the selected D-input level when OE is low; high-impedance when OE is high. Capable of driving up to 15 LSTTL loads at ±6 mA at 5 V.
6 W tri_state Inverted (complementary) 3-state data output. Drives the inverse of the selected D-input when OE is low; high-impedance when OE is high.
7 OE input Active-low output enable (strobe). When OE is low, the selected data appears on Y and W. When OE is high, both Y and W are placed in the high-impedance (3-state) condition.
8 GND power_in Ground (0 V) reference for the device.
9 C input Select input C (MSB of the 3-bit binary select). Together with B and A, chooses 1-of-8 data inputs D0-D7.
10 B input Select input B (middle bit of the 3-bit binary select).
11 A input Select input A (LSB of the 3-bit binary select).
12 D7 input Data input 7. Selected when C=H, B=H, A=H.
13 D6 input Data input 6. Selected when C=H, B=H, A=L.
14 D5 input Data input 5. Selected when C=H, B=L, A=H.
15 D4 input Data input 4. Selected when C=H, B=L, A=L.
16 VCC power_in Positive supply voltage, 2 V to 6 V (recommended). Absolute maximum 7 V. Bypass with a 0.1-µF capacitor placed close to the pin.

Key specifications

Parameter Value
Manufacturer Texas Instruments
Package SOIC-16
Category Logic
Pins 16

Ordering variants

Same part, different packaging or reel option.

  • SN74HC251DRD
  • SN74HC251DR
  • SN74HC251DRDB
  • SN74HC251DRDBR
  • SN74HC251DRN
  • SN74HC251DRNS
  • SN74HC251DRNSR
  • SN74HC251DRPW
  • SN74HC251DRPWR
  • SN74HC251DRJ
  • SN74HC251DRFK

CAD (KiCad official)

  • Symbol: SN74HC251DR
  • 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: Texas Instruments datasheet (31 pp, sha256 407441728ca2e20f, 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