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Contents

README

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CD74HCT640M

Texas Instruments · Buffer/Driver/Transceiver · SOIC-20-300mil

CD74HCT640M from Texas Instruments, in a SOIC-20-300mil. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 DIR input Direction control input: selects A-to-B or B-to-A data flow; HCT input levels VIL 0.8V max, VIH 2V min.
2 A0 bidirectional A-bus I/O 0 (three-state); output is inverted version of B0 input when enabled.
3 A1 bidirectional A-bus I/O 1 (three-state); output is inverted version of B1 input when enabled.
4 A2 bidirectional A-bus I/O 2 (three-state); output is inverted version of B2 input when enabled.
5 A3 bidirectional A-bus I/O 3 (three-state); output is inverted version of B3 input when enabled.
6 A4 bidirectional A-bus I/O 4 (three-state); output is inverted version of B4 input when enabled.
7 A5 bidirectional A-bus I/O 5 (three-state); output is inverted version of B5 input when enabled.
8 A6 bidirectional A-bus I/O 6 (three-state); output is inverted version of B6 input when enabled.
9 A7 bidirectional A-bus I/O 7 (three-state); output is inverted version of B7 input when enabled.
10 GND power_in Ground reference (0V).
11 B7 bidirectional B-bus I/O 7 (three-state); output is inverted version of A7 input when enabled.
12 B6 bidirectional B-bus I/O 6 (three-state); output is inverted version of A6 input when enabled.
13 B5 bidirectional B-bus I/O 5 (three-state); output is inverted version of A5 input when enabled.
14 B4 bidirectional B-bus I/O 4 (three-state); output is inverted version of A4 input when enabled.
15 B3 bidirectional B-bus I/O 3 (three-state); output is inverted version of A3 input when enabled.
16 B2 bidirectional B-bus I/O 2 (three-state); output is inverted version of A2 input when enabled.
17 B1 bidirectional B-bus I/O 1 (three-state); output is inverted version of A1 input when enabled.
18 B0 bidirectional B-bus I/O 0 (three-state); output is inverted version of A0 input when enabled.
19 OE input Active-low output enable: low enables outputs, high puts A and B ports in high impedance.
20 VCC power_in Supply voltage; 4.5V to 5.5V for HCT types, with 0.1 µF bypass capacitor recommended.

Key specifications

Parameter Value
Manufacturer Texas Instruments
Package SOIC-20-300mil
Category Logic ICs
Pins 20

CAD (KiCad official)

  • Symbol: CD74HCT640M
  • Footprint: Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm
  • 3D model: SOIC-20-300mil (KiCad packages3D, STEP)
  • 3D model files: cd74hct640m-etched.step / cd74hct640m-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); cd74hct640m.step / cd74hct640m.glb are the bare package body.

Provenance

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

  • Datasheet: Texas Instruments datasheet (19 pp, sha256 21ee67f9e5d6228b, retrieved 2026-10-08, tier: lcsc)
  • Datasheet language: Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-sonnet-5-5 (text+vision), consensus claude-opus-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF