# 0437001.WR

**Littelfuse** · Disposable Fuses · 1206

0437001.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 | Fuse terminal (Ag/Ni/Sn termination), non-polarized; 1A rated, 63 V max, 50 A @ 63 V AC/DC interrupting rating. |
| 2 | 2 | passive | Fuse terminal (Ag/Ni/Sn termination), non-polarized; 1A rated, 63 V max, 50 A @ 63 V AC/DC interrupting rating. |

## 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 25ºC, 100% of ampere rating (250mA-8A range) |  | 4 |  |  | hours | 100% of rated current, 25ºC; 1A is within 250mA-8A | 1 |
| Opening time at 25ºC, 250% of ampere rating (750mA-8A range) |  |  |  | 5 | seconds | 250% of rated current, 25ºC; 1A is within 750mA-8A | 1 |
| Opening time at 25ºC, 350% of ampere rating (750mA-8A range) |  |  |  | 1 | seconds | 350% of rated current, 25ºC; 1A is within 750mA-8A | 1 |
| Max. Voltage Rating |  |  |  | 63 | V | Amp code 001. (1A) | 1 |
| Interrupting Rating |  |  |  | 50 | A | 50 A @ 63 V AC/DC; AC at unity power factor, DC time constant < 0.8 msec | 1 |
| Operating Temperature |  | -55 |  | 150 | ºC | Series operating temperature range | 1 |
| Continuous operation current derating |  |  |  | 80 | % | Devices operated continuously at no more than 80% of rated current | 1 |
| Wave soldering temperature |  |  |  | 260 | °C | Wave soldering, 10 seconds max | 2 |
| Nominal Resistance |  |  | 0.42 |  | Ohms | Measured with < 10% rated current | 1 |
| Nominal Melting I2t |  |  | 0.1 |  | A2Sec. | Nominal, 1A amp code 001. | 1 |
| Nominal Voltage Drop At Rated Current |  |  | 0.41 |  | V | Measured at rated current after temperature has stabilized | 1 |
| Nominal Power Dissipation At Rated Current |  |  | 0.41 |  | W | At rated current (1A) | 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: `0437001.WR`
- Footprint: `Fuse:Fuse_1206_3216Metric`
- 3D model: 1206 (KiCad packages3D, STEP)
- 3D model files: `0437001-wr-etched.step` / `0437001-wr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `0437001-wr.step` / `0437001-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/8588917739503702016) (3 pp, sha256 `c2236d59abc0fa90`, retrieved 2026-10-18, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-5-5` (text+vision), consensus `claude-opus-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/0437001-wr-datasheet.pdf)