# MMSZ5221B

**hongjiacheng** · Zener Diodes · SOD-123

MMSZ5221B from hongjiacheng, 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, the end marked with the cathode line; the zener voltage VZ (2.28 V min to 2.52 V max for MMSZ5221B, 2.4 V nominal at IZT=20 mA) appears on this pin when reverse biased. |
| 2 | A | passive | Anode, the end opposite the cathode line; forward voltage VF is 0.9 V at IF=10 mA, with power dissipation limited to 500 mW. |

## Key specifications

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

## CAD (KiCad official)

- Symbol: `MMSZ5221B`
- Footprint: `Diode_SMD:D_SOD-123F`
- 3D model: SOD-123 (KiCad packages3D, STEP)
- 3D model files: `mmsz5221b-etched.step` / `mmsz5221b-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mmsz5221b.step` / `mmsz5221b.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [hongjiacheng datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8604441806629052416) (5 pp, sha256 `fec00843f279bccf`, retrieved 2026-10-09, 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/mmsz5221b-datasheet.pdf)