# SM30T21AY

**STMicroelectronics** · TVS · SMC(DO-214AB)

SM30T21AY from STMicroelectronics, in a SMC(DO-214AB). 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 | STMicroelectronics |
| Package | SMC(DO-214AB) |
| Category | Circuit Protection |
| 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 |
|---|---|---|---|---|---|---|---|
| Reverse leakage current at 25 °C | IRM |  |  | 0.2 | µA | at VRM 18 V, 25 °C | 3 |
| Reverse leakage current at 85 °C | IRM |  |  | 1 | µA | at VRM 18 V, 85 °C | 3 |
| Breakdown voltage | VBR | 20 |  |  | V | at IBR 1 mA | 3 |
| Breakdown voltage | VBR |  | 21.1 |  | V | at IBR 1 mA | 3 |
| Breakdown voltage | VBR |  |  | 22.2 | V | at IBR 1 mA | 3 |
| Clamping voltage | VCL |  |  | 29.2 | V | 10/1000 µs, IPP 103 A | 3 |
| Peak pulse current | IPP |  |  | 103 | A | 10/1000 µs | 3 |
| Dynamic resistance | RD |  |  | 68 | mΩ | 10/1000 µs | 3 |
| Clamping voltage | VCL |  |  | 39.3 | V | 8/20 µs, IPP 800 A | 3 |
| Peak pulse current | IPP |  |  | 800 | A | 8/20 µs | 3 |
| Dynamic resistance | RD |  |  | 21.4 | mΩ | 8/20 µs | 3 |
| Temperature coefficient of breakdown voltage | αT |  | 9.2 |  | 10-4/°C |  | 3 |
| Peak pulse power dissipation | PPP |  |  | 3000 | W | Tj initial = Tamb | 2 |
| Peak pulse voltage ISO10605 contact discharge | VPP | -30 |  | 30 | kV | ISO10605 C = 330 pF, R = 330 Ω, contact discharge | 2 |
| Peak pulse voltage ISO10605 air discharge | VPP | -30 |  | 30 | kV | ISO10605 C = 330 pF, R = 330 Ω, air discharge | 2 |
| Peak pulse voltage ISO10605/IEC 61000-4-2 contact discharge | VPP | -30 |  | 30 | kV | ISO10605 / IEC 61000-4-2 C = 150 pF, R = 330 Ω, contact discharge | 2 |
| Peak pulse voltage ISO10605/IEC 61000-4-2 air discharge | VPP | -30 |  | 30 | kV | ISO10605 / IEC 61000-4-2 C = 150 pF, R = 330 Ω, air discharge | 2 |
| Storage temperature range | Tstg | -65 |  | 175 | °C |  | 2 |
| Operating junction temperature range | Tj | -55 |  | 175 | °C |  | 2 |
| Maximum lead temperature for soldering | TL |  |  | 260 | °C | during 10 s | 2 |

## Materials and finish

As the datasheet states them (page.json `metadata.appearance`; the 3D model's colours follow it).

| Part | Material | Colour / plating | Datasheet says | Page |
|---|---|---|---|---|
| contacts |  | tin | • Lead finishing: matte tin plating Complies with the following standards | 1 |

## CAD (KiCad official)

- Symbol: `SM30T21AY`
- Footprint: `Diode_SMD:D_SMC`
- 3D model: SMC(DO-214AB) (KiCad packages3D, STEP)
- 3D model files: `sm30t21ay-etched.step` / `sm30t21ay-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `sm30t21ay.step` / `sm30t21ay.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [STMicroelectronics datasheet](https://www.st.com/resource/en/datasheet/sm30t21ay.pdf) (16 pp, sha256 `f6d47dc33b5be94c`, retrieved 2026-11-02, tier: manufacturer)
- **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/sm30t21ay-datasheet.pdf)