# MMBZ5231B

**DOWO** · Zener Diodes · SOT-23

MMBZ5231B from DOWO, in a SOT-23. 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 | passive | Anode of the zener diode; the 5.1V nominal zener (4.85V min to 5.36V max at IZT=20mA) is reached with this pin negative relative to pin 3. |
| 2 | NC | unconnected | No connection; the package drawing shows pin 2 with no connection to the diode symbol. |
| 3 | K | passive | Cathode of the zener diode, which is positive in normal zener operation; power dissipation is 500mW maximum. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | DOWO |
| Package | SOT-23 |
| Category | Diodes |
| Pins | 3 |

## CAD (KiCad official)

- Symbol: `MMBZ5231B`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `mmbz5231b-etched.step` / `mmbz5231b-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mmbz5231b.step` / `mmbz5231b.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [DOWO datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8590917998436179968) (4 pp, sha256 `8bfac1932bb0cf76`, 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/mmbz5231b-datasheet.pdf)