# MMBZ5254B

**Changjing** · Zener Diodes · SOT-23

MMBZ5254B from Changjing, 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 | Zener anode, shown on the page 1 symbol as the diode input; the MMBZ5254B has a 27V nominal Zener voltage (25.65V to 28.35V) at IZT = 5.0mA. |
| 2 | NC | unconnected | Pin 2 is drawn as an isolated terminal with no internal connection in the page 1 symbol. |
| 3 | K | passive | Zener cathode, the bar side of the diode symbol; maximum leakage is 0.1µA at VR = 21V and power dissipation is limited to 300mW. |

## Key specifications

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

## 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 | 25.65 | 27 | 28.35 | V | @ IZT = 5.0 mA | 2 |
| Maximum Zener Impedance | ZZT |  |  | 41 | Ω | @ IZT = 5.0 mA, f = 1kHz | 2 |
| Maximum Zener Impedance (knee) | ZZK |  |  | 600 | Ω | @ IZK = 0.25mA | 2 |
| Maximum Reverse Leakage Current | IR |  |  | 0.1 | µA | @ VR = 21 V | 2 |
| Forward Voltage | VF |  |  | 0.9 | V | IF = 10mA | 1 |
| Power Dissipation | PD |  |  | 300 | mW | Ta = 25℃ | 1 |
| Operation Junction and Storage Temperature Range | TJ,TSTG | -55 |  | 150 | ℃ |  | 1 |
| Thermal Resistance Junction to Ambient | RθJA |  |  | 417 | ℃/W |  | 1 |
| Zener Test Current | IZT |  | 5 |  | mA | Test current for VZ and ZZT | 2 |
| Nominal Zener Voltage | VZ nom |  | 27 |  | V | @ IZT | 2 |

## CAD (KiCad official)

- Symbol: `MMBZ5254B`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `mmbz5254b-etched.step` / `mmbz5254b-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mmbz5254b.step` / `mmbz5254b.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Changjing datasheet](docs/mmbz5254b-datasheet.pdf) (5 pp, sha256 `eab0dbad2cbe9e7d`, retrieved 2026-10-22, 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/mmbz5254b-datasheet.pdf)