# SZ1SMB43AT3G

**Littelfuse** · TVS · SMB

SZ1SMB43AT3G 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 | Cathode of the unidirectional TVS diode, marked by the color band; connect to the positive/protected line, with VRWM of 43 V and VBR of 47.8 V to 52.8 V at 1.0 mA. |
| 2 | Anode | passive | Anode of the unidirectional TVS diode, normally connected to ground; clamps at VC 69.4 V at IPP 8.6 A. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Littelfuse |
| Package | SMB |
| Category | TVS/Fuse/Board Level 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 | 47.8 | 50.3 | 52.8 | V | @ IT = 1.0 mA, TA=25°C | 3 |
| Working Peak Reverse Voltage | VRWM |  | 43 |  | V |  | 3 |
| Maximum Reverse Leakage Current | IR |  |  | 5 | µA | @ VRWM | 3 |
| Clamping Voltage | VC |  |  | 69.4 | V | @ IPP = 8.6 A | 3 |
| Maximum Reverse Peak Pulse Current | IPP |  |  | 8.6 | A |  | 3 |
| Forward Voltage | VF |  |  | 3.5 | V | IF = 30 A, TA=25°C, uni-directional | 2 |
| Peak Power Dissipation | PPK |  |  | 600 | W | TL = 25°C, Pulse Width = 1 ms, 10/1000 µs non-repetitive | 1 |
| DC Power Dissipation (lead) | PD |  |  | 3 | W | TL = 75°C, zero lead length, 1" square copper pad FR-4 | 1 |
| DC Power Dissipation (ambient) | PD |  |  | 0.55 | W | TA = 25°C, FR-4 board, minimum recommended footprint | 1 |
| Forward Surge Current | IFSM |  |  | 100 | A | TA = 25°C, 1/2 sine wave PW = 8.3 ms, uni-directional only | 1 |
| Operating and Storage Temperature Range | TJ, Tstg | -65 |  | 175 | °C |  | 1 |
| Thermal Resistance Junction-to-Lead | RƟJL |  |  | 25 | °C/W |  | 1 |
| Thermal Resistance Junction-to-Ambient | RƟJA |  |  | 100 | °C/W |  | 1 |
| Capacitance | C |  | 400 |  | pF | Bias Voltage = 0 V, F = 1 MHz, TJ = 25°C | 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 |
|---|---|---|---|---|
| contacts |  | tin | the terminal finish material is tin(Sn) (IPC/JEDEC J-STD￾609A.01) | 1 |

## CAD (KiCad official)

- Symbol: `SZ1SMB43AT3G`
- Footprint: `Diode_SMD:D_SMB`
- 3D model: SMB (KiCad packages3D, STEP)
- 3D model files: `sz1smb43at3g-etched.step` / `sz1smb43at3g-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `sz1smb43at3g.step` / `sz1smb43at3g.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Littelfuse datasheet](docs/sz1smb43at3g-datasheet.pdf) (7 pp, sha256 `9b427104bf8c86ce`, retrieved 2026-10-27, 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/sz1smb43at3g-datasheet.pdf)