# SZ1SMB48CAT3G

**Littelfuse** · ESD And Surge Protection (TVS/ESD) · SMB

SZ1SMB48CAT3G from Littelfuse, in a 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 | Cathode | passive | Terminal labelled Cathode on the SMB package marking diagram, where the cathode mark (color band) identifies the cathode of uni-directional parts; the datasheet gives no polarity marking for the bi-directional SZ1SMB48CAT3G, whose working peak reverse voltage is 48 V with a 5.0 µA maximum reverse leakage at VRWM. |
| 2 | Anode | passive | Terminal labelled Anode on the SMB package marking diagram, paired with pin 1 for uni-directional parts; the datasheet gives no polarity marking for the bi-directional SZ1SMB48CAT3G, so both terminals are treated as interchangeable. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Littelfuse |
| Package | 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 |
|---|---|---|---|---|---|---|---|
| Breakdown voltage | VBR | 53.3 | 56.11 | 58.9 | V | @ IT = 1.0 mA (Note 7) | 4 |
| Maximum reverse leakage current | IR |  |  | 5 | µA | @ VRWM = 48 V | 4 |
| Clamping voltage | VC |  | 77.4 |  | V | @ IPP = 7.7 A (Note 8) | 4 |
| Working peak reverse voltage | VRWM |  | 48 |  | V |  | 4 |
| Maximum reverse peak pulse current | IPP |  |  | 7.7 | A | Surge waveform per Note 8 | 4 |
| Peak power dissipation | PPK |  |  | 600 | W | TL = 25°C, pulse width 1 ms, 10/1000 µs non-repetitive (Note 1) | 1 |
| Operating and storage temperature range | TJ, Tstg | -65 |  | 175 | °C |  | 1 |
| DC power dissipation (lead) | PD |  |  | 3 | W | TL = 75°C, measured zero lead length (Note 2) | 1 |
| Derating above 75°C (lead) | PD |  | 40 |  | mW/°C | Derate above 75°C | 1 |
| Thermal resistance junction-to-lead | RθJL |  |  | 25 | °C/W |  | 1 |
| DC power dissipation (ambient) | PD |  |  | 0.55 | W | TA = 25°C (Note 3) | 1 |
| Derating above 25°C (ambient) | PD |  | 4.4 |  | mW/°C | Derate above 25°C | 1 |
| Thermal resistance junction-to-ambient | RθJA |  |  | 100 | °C/W | Note 3 (FR-4, Littelfuse minimum recommended footprint) | 1 |

## 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 | the terminal finish material is tin(Sn) (IPC/JEDEC J-STD￾609A.01) | 1 |

## CAD (KiCad official)

- Symbol: `SZ1SMB48CAT3G`
- Footprint: `Diode_SMD:D_SMB`
- 3D model: SMB (KiCad packages3D, STEP)
- 3D model files: `sz1smb48cat3g-etched.step` / `sz1smb48cat3g-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `sz1smb48cat3g.step` / `sz1smb48cat3g.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Littelfuse datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8590475292524240896) (7 pp, sha256 `b0ca6934cecaf5e0`, retrieved 2026-10-16, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-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/sz1smb48cat3g-datasheet.pdf)