SN74HC138

@@ -0,0 +1,60 @@+# SN74HC138++**Texas Instruments** · 3-to-8 line decoder / demux · SOIC-16++A 3-to-8 line decoder/demultiplexer in high-speed CMOS, SOIC-16. Three binary select inputs (A, B, C) drive eight mutually exclusive active-low outputs (Y0-Y7): the addressed output goes low while the other seven stay high. Three enable inputs (G1 active-high, G2A and G2B active-low) gate the whole device, which makes it easy to chain several for wider address decoding or to use as a 1-of-8 demultiplexer for a data line. Runs 2-6 V.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | A | input | Select input A (least significant bit of the 3-bit binary address selecting which Y output is asserted low). |+| 2 | B | input | Select input B (middle bit of the 3-bit binary address). |+| 3 | C | input | Select input C (most significant bit of the 3-bit binary address). |+| 4 | G2A | input | Active-low enable A. Must be low (together with G2B low and G1 high) to enable outputs; otherwise all Y outputs are forced high. |+| 5 | G2B | input | Active-low enable B. Must be low (together with G2A low and G1 high) to enable outputs. |+| 6 | G1 | input | Active-high enable. Must be high (together with G2A and G2B low) to enable outputs. |+| 7 | Y7 | output | Decoded output 7 (most significant, active low). Asserts low when enabled and CBA = 111. Drive capability ±4 mA at VCC = 5 V. |+| 8 | GND | power_in | Ground reference (0 V). |+| 9 | Y6 | output | Decoded output 6 (active low). Asserts low when enabled and CBA = 110. |+| 10 | Y5 | output | Decoded output 5 (active low). Asserts low when enabled and CBA = 101. |+| 11 | Y4 | output | Decoded output 4 (active low). Asserts low when enabled and CBA = 100. |+| 12 | Y3 | output | Decoded output 3 (active low). Asserts low when enabled and CBA = 011. |+| 13 | Y2 | output | Decoded output 2 (active low). Asserts low when enabled and CBA = 010. |+| 14 | Y1 | output | Decoded output 1 (active low). Asserts low when enabled and CBA = 001. |+| 15 | Y0 | output | Decoded output 0 (least significant, active low). Asserts low when enabled and CBA = 000. |+| 16 | VCC | power_in | Positive supply voltage, 2 V to 6 V (nominal 5 V). |++## Key specifications++| Parameter | Value |+|---|---|+| Type | 3-to-8 decoder / demultiplexer |+| Select inputs | 3 (A/B/C) |+| Outputs | 8 active-low (Y0-Y7) |+| Enables | G1 (high) + G2A/G2B (low) |+| Logic family | HC (high-speed CMOS) |+| Supply voltage | 2-6 V |+| Package | SOIC-16 |+| Body (L×W×H) | 9.9 × 3.9 × 1.75 mm |++## Ordering variants++- `SN74HC138D (SOIC-16, tube)`+- `SN74HC138DR (SOIC-16, tape & reel)`++## CAD (KiCad official)++- Symbol: `74xx:74HC138`+- Footprint: `Package_SO:SOIC-16_3.9x9.9mm_P1.27mm`+- 3D model: SOIC-16 (KiCad packages3D)++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/sn74hc138.pdf) (35 pp, sha256 `ba6cab88a44c1c9a`, 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](docs/sn74hc138-datasheet.pdf)

@@ -0,0 +1,36 @@+{+  "slug": "sn74hc138",+  "version": "0.1.0",+  "type": "component",+  "description": "TI 3-to-8 line decoder/demultiplexer, SOIC-16. Three enables, eight active-low outputs, HC CMOS 2-6 V. Datasheet-verified.",+  "tags": [+    "component",+    "logic",+    "decoder",+    "demultiplexer",+    "74hc",+    "soic-16",+    "texas-instruments"+  ],+  "dependencies": {},+  "hero": {+    "type": "image",+    "path": "docs/hero.png"+  },+  "files": [+    "page.json",+    "README.md",+    "sn74hc138.kicad_sym",+    "sn74hc138.kicad_mod",+    "sn74hc138.glb",+    "docs/hero.png",+    "docs/sn74hc138-datasheet.pdf",+    "viewers/symbol.html",+    "viewers/footprint.html"+  ],+  "visibility": "public",+  "author": {+    "name": "Ray",+    "email": "[email protected]"+  }+}\ No newline at end of file