# SMBJ78AQ

**Yangzhou Yangjie Elec Tech** · Electrostatic And Surge Protection (TVS/ESD) · DO-214AA(SMB)

SMBJ78AQ from Yangzhou Yangjie Elec Tech, in a DO-214AA(SMB). 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 | Yangzhou Yangjie Elec Tech |
| Package | DO-214AA(SMB) |
| 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 |
|---|---|---|---|---|---|---|---|
| Maximum instantaneous forward voltage | VF |  |  | 3.5 | V | at 50A for unidirectional only (3) | 1 |
| Peak pulse power dissipation | PPPM |  |  | 600 | W | 10/1000us waveform (1)(2)(Fig.1) | 1 |
| Power dissipation | PD |  |  | 5 | W | on infinite heat sink at TL=75℃ | 1 |
| Peak forward surge current | IFSM |  |  | 100 | A | 8.3 ms single half sine-wave, unidirectional only (2) | 1 |
| Operating junction temperature | TJ | -55 |  | 175 | ℃ |  | 1 |
| Storage temperature range | TSTG | -55 |  | 175 | ℃ |  | 1 |
| Breakdown voltage | VBR | 86.7 |  | 95.8 | V | IT=1 mA | 2 |
| Test current | IT |  | 1 |  | mA |  | 2 |
| Maximum reverse leakage | IR |  |  | 1 | μA | at VRWM | 2 |
| Working peak reverse voltage | VRWM |  | 78 |  | V |  | 2 |
| Maximum reverse surge current | IPP |  |  | 4.8 | A |  | 2 |
| Maximum clamping voltage | Vc |  |  | 126 | V | @ IPP | 2 |
| Thermal resistance, junction to lead (typical) | RθJL |  | 20 |  | ℃/W | junction to lead | 3 |
| Thermal resistance, junction to ambient (typical) | RθJA |  | 100 |  | ℃/W | junction to ambient | 3 |

## 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 |
|---|---|---|---|---|
| housing |  | black | 4. Body color: Black | 3 |
| contacts |  | tin | ● Terminals: Matte tin plated leads, solderable per J-STD-002 and JESD22-B102 | 1 |

## CAD (KiCad official)

- Symbol: `SMBJ78AQ`
- Footprint: `Diode_SMD:D_SMB`
- 3D model: DO-214AA(SMB) (KiCad packages3D, STEP)
- 3D model files: `smbj78aq-etched.step` / `smbj78aq-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `smbj78aq.step` / `smbj78aq.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Yangzhou Yangjie Elec Tech datasheet](docs/smbj78aq-datasheet.pdf) (6 pp, sha256 `c858e6d6adc08fc3`, retrieved 2026-10-30, 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/smbj78aq-datasheet.pdf)