# BZT52C18T

**MDD（Microdiode Electronics）** · Zener Diodes · SOD-523

BZT52C18T from MDD（Microdiode Electronics）, in a SOD-523. 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, identified by the marking bar on the body; the zener is reverse-biased with this pin positive, with VZ nominal 18V (16.8V to 19.1V) at IZT = 5mA. |
| 2 | A | passive | Anode of the zener diode, the end opposite the cathode marking bar. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | MDD（Microdiode Electronics） |
| Package | SOD-523 |
| 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 | 16.8 | 18 | 19.1 | V | IZT = 5 mA | 2 |
| Maximum Zener Impedance | ZZT |  |  | 45 | Ω | IZT = 5 mA | 2 |
| Maximum Zener Impedance (knee) | ZZK |  |  | 225 | Ω | IZK = 1.0 mA | 2 |
| Maximum Reverse Current | IR |  |  | 0.1 | μA | VR = 12.6 V | 2 |
| Typical Temperature Coefficient |  | 12.4 |  | 16 | mV/℃ | IZTC = 5 mA | 2 |
| Forward Voltage | VF |  |  | 0.9 | V | IF = 10 mA | 1 |
| Power Dissipation | Pd |  |  | 20 | mW | Note 1 | 1 |
| Typical thermal resistance, junction to ambient | RθJA |  | 55 |  | /W | PCB mounted with 2.0" x 2.0" (5 x 5 cm) copper pads | 1 |
| Junction Temperature | Tj |  |  | 150 | ℃ |  | 1 |
| Storage Temperature Range | Tstg | -65 |  | 150 | ℃ |  | 1 |

## CAD (KiCad official)

- Symbol: `BZT52C18T`
- Footprint: `Diode_SMD:D_SOD-523`
- 3D model: SOD-523 (KiCad packages3D, STEP)
- 3D model files: `bzt52c18t-etched.step` / `bzt52c18t-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bzt52c18t.step` / `bzt52c18t.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [MDD（Microdiode Electronics） datasheet](docs/bzt52c18t-datasheet.pdf) (4 pp, sha256 `e95e3687fd67bb8f`, 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/bzt52c18t-datasheet.pdf)