# HMMSZ5242BT1G

**HXY MOSFET** · Zener Diodes · SOD-123

HMMSZ5242BT1G from HXY MOSFET, in a SOD-123. 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 | K | passive | Cathode, marked by the marking bar on the package; this side goes positive for zener (reverse) operation, with 500 mW power dissipation on ceramic PCB. |
| 2 | A | passive | Anode, the end opposite the marking bar; forward voltage is 0.85 V at IF = 10 mA. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | HXY MOSFET |
| Package | SOD-123 |
| Category | Diodes |
| Pins | 2 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Zener voltage (nominal 12 V, Min) | VZ | 11.76 | 12 | 12.24 | V | Ta=25℃ unless otherwise specified; IZT not reliably aligned in extracted text | 2 |
| Power dissipation | PD |  |  | 500 | mW | Device mounted on ceramic PCB; 5.0mm×7.0mm with pad areas 35 mm2 | 1 |
| Forward voltage | VF |  |  | 0.85 | V | @IF = 10mA | 1 |
| Junction temperature | Tj |  |  | 150 | ℃ |  | 1 |
| Storage temperature range | Tstg | -55 |  | 150 | ℃ |  | 1 |
| Thermal resistance, junction to ambient air | RθJA |  |  | 556 | ℃/W | Device mounted on ceramic PCB; 5.0mm×7.0mm with pad areas 35 mm2 | 1 |

## CAD (KiCad official)

- Symbol: `HMMSZ5242BT1G`
- Footprint: `Diode_SMD:D_SOD-123F`
- 3D model: SOD-123 (KiCad packages3D, STEP)
- 3D model files: `hmmsz5242bt1g-etched.step` / `hmmsz5242bt1g-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `hmmsz5242bt1g.step` / `hmmsz5242bt1g.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [HXY MOSFET datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8603008251437072384) (5 pp, sha256 `0ce80cd1655e5204`, retrieved 2026-10-19, tier: lcsc)
- **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](docs/hmmsz5242bt1g-datasheet.pdf)