# SMBJ78A

**FOSAN** · ESD And Surge Protection (TVS/ESD) · SMB(DO-214AA)

SMBJ78A from FOSAN, in a SMB(DO-214AA). 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 | FOSAN |
| Package | SMB(DO-214AA) |
| 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 |
|---|---|---|---|---|---|---|---|
| Breakdown voltage (unidirectional, A suffix) | VBR | 86.7 |  | 99.7 | V | IT = 1 mA | 2 |
| Clamping voltage | VC |  | 126 |  | V | @IPP = 4.7 A | 2 |
| Reverse leakage current | IR |  | 5 |  | µA | @VRWM | 2 |
| Reverse stand-off working voltage | VRWM |  | 78 |  | V |  | 2 |
| Peak Power Dissipation | PPK |  |  | 600 | W |  | 1 |
| Power Dissipation | PD |  |  | 5 | W |  | 1 |
| Peak Forward Surge Current (UNI) | IFSM |  |  | 100 | A | UNI | 1 |
| Forward Voltage (UNI) | VF |  |  | 3.5 | V | @IF=35A | 1 |
| Junction/Storage Temperature | TJ,Tstg | -55 |  | 150 | ℃ |  | 1 |

## CAD (KiCad official)

- Symbol: `SMBJ78A`
- Footprint: `Diode_SMD:D_SMB`
- 3D model: SMB(DO-214AA) (KiCad packages3D, STEP)
- 3D model files: `smbj78a-etched.step` / `smbj78a-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `smbj78a.step` / `smbj78a.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [FOSAN datasheet](docs/smbj78a-datasheet.pdf) (4 pp, sha256 `3669787e11f43216`, retrieved 2026-10-21, tier: lcsc)
- **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/smbj78a-datasheet.pdf)