# MM3Z27B

**ST Semtech** · Zener Diodes · SOD-323

MM3Z27B from ST Semtech, in a SOD-323. 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 | Cathode | passive | Cathode of the Zener diode (marked by the cathode line); MM3Z27B has VZ of 26.19 V to 27.53 V at IZT = 5 mA. |
| 2 | Anode | passive | Anode of the Zener diode; total power dissipation is limited to 300 mW max. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | ST Semtech |
| Package | SOD-323 |
| 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 | VZT | 26.19 |  | 27.53 | V | IZT = 5 mA, Ta = 25℃, pulsed 20 ms | 2 |
| Dynamic Impedance | ZZT |  |  | 150 | Ω | at IZT = 5 mA | 2 |
| Reverse Leakage Current | IR |  |  | 0.1 | μA | VR = 21 V | 2 |
| Forward Voltage | VF |  |  | 0.9 | V | IF = 10 mA | 2 |
| Power Dissipation | Ptot |  |  | 300 | mW | Ta = 25℃ | 1 |
| Junction Temperature | Tj |  |  | 150 | ℃ | Ta = 25℃ | 1 |
| Storage Temperature Range | TStg | -55 |  | 150 | ℃ | Ta = 25℃ | 1 |
| Thermal Resistance Junction to Ambient Air | RthA |  |  | 417 | ℃/W | Device mounted on FR-4 PC board, 2oz copper, minimum recommended pad layout | 1 |

## Materials and finish

As the datasheet states them (page.json `metadata.appearance`; the 3D model's colours follow it).

| Part | Material | Colour / plating | Datasheet says | Page |
|---|---|---|---|---|
| housing | Abs |  | plastic SMD SOD-323 package Absolute Maximum Ratings (Ta = 25℃) | 1 |

## CAD (KiCad official)

- Symbol: `MM3Z27B`
- Footprint: `Diode_SMD:D_SOD-323`
- 3D model: SOD-323 (KiCad packages3D, STEP)
- 3D model files: `mm3z27b-etched.step` / `mm3z27b-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mm3z27b.step` / `mm3z27b.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [ST Semtech datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8603065786927886336) (4 pp, sha256 `e3d2ccefaaf4a468`, retrieved 2026-10-22, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-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/mm3z27b-datasheet.pdf)