74HC138D

@@ -0,0 +1,57 @@+# 74HC138D++**Nexperia** · Signal Switches / Encoders & Decoders / Multiplexers · SOIC-16++74HC138D 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 | A0 | input | Address input 0 (LSB). Binary select input for the decoder; combined with A1 and A2 selects which of the eight outputs is asserted LOW when the device is enabled. |+| 2 | A1 | input | Address input 1. Binary select input for the decoder. |+| 3 | A2 | input | Address input 2 (MSB). Binary select input for the decoder. |+| 4 | E1 | input | Enable input 1, active LOW. Must be LOW (together with E2 LOW and E3 HIGH) to enable the selected output; otherwise all outputs are HIGH. |+| 5 | E2 | input | Enable input 2, active LOW. Must be LOW (together with E1 LOW and E3 HIGH) to enable outputs. |+| 6 | E3 | input | Enable input 3, active HIGH. Must be HIGH (together with E1 and E2 LOW) to enable outputs. |+| 7 | Y7 | output | Decoder output 7, active LOW. Asserted LOW when A2=A1=A0=1 and the device is enabled. |+| 8 | GND | power_in | Ground reference (0 V). Common return for supply and logic signals. |+| 9 | Y6 | output | Decoder output 6, active LOW. Asserted LOW when A2A1A0 = 110 and device is enabled. |+| 10 | Y5 | output | Decoder output 5, active LOW. Asserted LOW when A2A1A0 = 101 and device is enabled. |+| 11 | Y4 | output | Decoder output 4, active LOW. Asserted LOW when A2A1A0 = 100 and device is enabled. |+| 12 | Y3 | output | Decoder output 3, active LOW. Asserted LOW when A2A1A0 = 011 and device is enabled. |+| 13 | Y2 | output | Decoder output 2, active LOW. Asserted LOW when A2A1A0 = 010 and device is enabled. |+| 14 | Y1 | output | Decoder output 1, active LOW. Asserted LOW when A2A1A0 = 001 and device is enabled. |+| 15 | Y0 | output | Decoder output 0, active LOW. Asserted LOW when A2A1A0 = 000 and device is enabled. |+| 16 | VCC | power_in | Positive supply voltage, 2.0 V to 6.0 V (recommended). Provides power to the internal logic. |++## Key specifications++| Parameter | Value |+|---|---|+| Manufacturer | Nexperia |+| Package | SOIC-16 |+| Category | Logic |+| Pins | 16 |++## Ordering variants++- `74HC138DD`+- `74HC138DPW`+- `74HC138DBQ`++## CAD (KiCad official)++- Symbol: `74HC138D`+- 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](https://assets.nexperia.com/documents/data-sheet/74HC138D.pdf) (15 pp, sha256 `645120bc441507e9`, 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/74hc138d-datasheet.pdf)

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