# 74HC138MT

**HGSEMI** · Signal Switches, Multiplexers, Decoders · TSSOP-16

74HC138MT from HGSEMI, in a TSSOP-16. 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 | A | input | Binary address data input A (weight 1) that selects which of the eight outputs Y0 to Y7 goes low. |
| 2 | B | input | Binary address data input B (weight 2) that selects which of the eight outputs Y0 to Y7 goes low. |
| 3 | C | input | Binary address data input C (weight 4) that selects which of the eight outputs Y0 to Y7 goes low. |
| 4 | G2B | input | Active-low enable input; it must be low, together with G2A low and G1 high, for the decoder to be enabled. |
| 5 | G2A | input | Active-low enable input; it must be low, together with G2B low and G1 high, for the decoder to be enabled. |
| 6 | G1 | input | Active-high enable input; it must be high, together with G2A and G2B low, for the decoder to be enabled. |
| 7 | Y7 | output | Active-low decoded parallel output 7, driven low when the address selects it and the enables are active. |
| 8 | GND | power_in | Ground reference pin for the device. |
| 9 | Y6 | output | Active-low decoded parallel output 6, driven low when the address selects it and the enables are active. |
| 10 | Y5 | output | Active-low decoded parallel output 5, driven low when the address selects it and the enables are active. |
| 11 | Y4 | output | Active-low decoded parallel output 4, driven low when the address selects it and the enables are active. |
| 12 | Y3 | output | Active-low decoded parallel output 3, driven low when the address selects it and the enables are active. |
| 13 | Y2 | output | Active-low decoded parallel output 2, driven low when the address selects it and the enables are active. |
| 14 | Y1 | output | Active-low decoded parallel output 1, driven low when the address selects it and the enables are active. |
| 15 | Y0 | output | Active-low decoded parallel output 0, driven low when the address selects it and the enables are active. |
| 16 | VCC | power_in | Positive supply pin; the recommended supply range is 2.0 V to 6.0 V (absolute maximum -0.5 V to 6.5 V). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | HGSEMI |
| Package | TSSOP-16 |
| Category | Logic |
| Pins | 16 |

## CAD (KiCad official)

- Symbol: `74HC138MT`
- Footprint: `Package_SO:TSSOP-16_4.4x5mm_P0.65mm`
- 3D model: TSSOP-16 (KiCad packages3D, STEP)
- 3D model files: `74hc138mt-etched.step` / `74hc138mt-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `74hc138mt.step` / `74hc138mt.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [HGSEMI datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8762802083769147392) (10 pp, sha256 `c1019058ded7c03f`, retrieved 2026-10-17, 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-haiku-5-5` (text), consensus `claude-sonnet-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](docs/74hc138mt-datasheet.pdf)