# 0440.250WR

**Littelfuse** · Disposable Fuses · 1206

0440.250WR 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 |
|---|---|---|---|---|---|---|---|
| Opening time at 100% of ampere rating (minimum) |  | 4 |  |  | hours | 100% of ampere rating; minimum | 1 |
| Opening time at 350% of ampere rating (maximum) |  |  |  | 5 | secs. | 350% of ampere rating at 25ºC; maximum | 1 |
| Max. voltage rating (rated voltage) |  |  |  | 125 | V |  | 1 |
| Operating temperature |  | -55 |  | 150 | °C |  | 1 |
| Continuous operation current (fraction of rated current) |  |  |  | 80 | % | Continuous operation; no more than 80% of rated current | 1 |
| Pb-free reflow peak temperature (TP) | TP |  |  | 260 | °C | Pb-free reflow; printed 260+0/-5 °C; do not exceed 260°C | 2 |
| Wave soldering temperature |  |  |  | 260 | °C | Wave soldering; 10 seconds max | 2 |
| Ampere rating |  |  | 0.25 |  | A | Amp code .250 | 1 |
| Interrupting rating (AC/DC) |  |  | 50 |  | A | @ 125 V AC/DC | 1 |
| Nominal resistance |  |  | 2.14 |  | Ohms | Measured with <10% rated current | 1 |
| Nominal melting I2t |  |  | 0.00649 |  | A2Sec. |  | 1 |
| Nominal voltage drop at rated current |  |  | 0.526 |  | V | At rated current after temperature has stabilized | 1 |
| Nominal power dissipation at rated current |  |  | 0.132 |  | W | At 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: Lead-free Glass | 3 |

## CAD (KiCad official)

- Symbol: `0440.250WR`
- Footprint: `Fuse:Fuse_1206_3216Metric`
- 3D model: 1206 (KiCad packages3D, STEP)
- 3D model files: `0440-250wr-etched.step` / `0440-250wr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `0440-250wr.step` / `0440-250wr.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/8588911213984432128) (3 pp, sha256 `39359c45db276d92`, retrieved 2026-10-18, 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/0440-250wr-datasheet.pdf)