# 0437004.WR

**Littelfuse** · Disposable Fuses · 1206

0437004.WR from Littelfuse, in a 1206. 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 | 1 | passive | Terminal 1 of an unpolarised fuse; either orientation. |
| 2 | 2 | passive | Terminal 2 of an unpolarised fuse; either orientation. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Littelfuse |
| Package | 1206 |
| 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 |
|---|---|---|---|---|---|---|---|
| Max. Voltage Rating |  |  |  | 63 | V |  | 1 |
| Ampere Rating |  |  | 4 |  | A |  | 1 |
| Nominal Resistance |  |  | 0.022 |  | Ohms | Measured with <10% rated current | 1 |
| Nominal Melting I2t |  |  | 1.024 |  | A2 Sec. |  | 1 |
| Nominal Voltage Drop At Rated Current |  |  | 0.13 |  | V | Measured at rated current after temperature has stabilized | 1 |
| Nominal Power Dissipation At Rated Current |  |  | 0.52 |  | W | At rated current | 1 |
| Opening Time at 25ºC (100% of ampere rating) |  | 4 |  |  | hours | 100% of ampere rating, 750mA-8A range is 250% row; this row applies to 250mA-8A, at 25ºC | 1 |
| Opening Time at 25ºC (250% of ampere rating) |  |  |  | 5 | seconds | 250% of ampere rating, 750mA-8A, at 25ºC | 1 |
| Opening Time at 25ºC (350% of ampere rating) |  |  |  | 1 | seconds | 350% of ampere rating, 750mA-8A, at 25ºC | 1 |
| Operating Temperature |  | -55 |  | 150 | ºC |  | 1 |
| Continuous Operating Current (recommended) |  |  |  | 80 | % | Continuous operation, percent of rated current | 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 | Terminations: Ag / Ni / Sn (100% Lead-free) Element Cover Coating: Ceramic/Lead-free | 3 |

## CAD (KiCad official)

- Symbol: `0437004.WR`
- Footprint: `Fuse:Fuse_1206_3216Metric`
- 3D model: 1206 (KiCad packages3D, STEP)
- 3D model files: `0437004-wr-etched.step` / `0437004-wr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `0437004-wr.step` / `0437004-wr.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/8756463922013069312) (3 pp, sha256 `cc8a5347bf86eeaf`, retrieved 2026-10-19, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins`, primary `two-terminal 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/0437004-wr-datasheet.pdf)