# MMSZ5256BS

**Changjing** · Zener Diodes · SOD-323

MMSZ5256BS from Changjing, 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 | K | passive | Cathode: the banded/marked end per the datasheet; pad 1 of the KiCad diode footprint. |
| 2 | A | passive | Anode. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Changjing |
| 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 | VZ | 28.5 | 30 | 31.5 | V | @IZT=4.2mA, Ta=25℃ | 2 |
| Test Current | IZT |  | 4.2 |  | mA | Ta=25℃ | 2 |
| Maximum Zener Impedance | ZZT |  |  | 49 | Ω | @IZT=4.2mA | 2 |
| Maximum Zener Impedance (knee) | ZZK |  |  | 600 | Ω | @IZK=0.25mA | 2 |
| Maximum Reverse Current | IR |  |  | 0.1 | uA | VR=23V | 2 |
| Forward Voltage | VF |  |  | 0.9 | V | IF=10mA, tested with pulses Tp≤1.0ms | 1 |
| Power Dissipation | PD |  |  | 200 | mW | Device mounted on ceramic PCB, 25 mm2 pad areas | 1 |
| Thermal Resistance, Junction to Ambient Air | RθJA |  | 625 |  | ℃/W | Device mounted on ceramic PCB, 25 mm2 pad areas | 1 |
| Operation Junction and Storage Temperature Range | TJ,Tstg | -55 |  | 150 | ℃ |  | 1 |

## CAD (KiCad official)

- Symbol: `MMSZ5256BS`
- Footprint: `Diode_SMD:D_SOD-323`
- 3D model: SOD-323 (KiCad packages3D, STEP)
- 3D model files: `mmsz5256bs-etched.step` / `mmsz5256bs-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mmsz5256bs.step` / `mmsz5256bs.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Changjing datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8590905924712144896) (5 pp, sha256 `72b04606355c189c`, retrieved 2026-10-22, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins`, primary `cathode-band convention` (convention), consensus `off` (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/mmsz5256bs-datasheet.pdf)