# MF-NSML300

**BOURNS** · Resettable Fuses · 1206

MF-NSML300 from BOURNS, 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 | BOURNS |
| 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 |
|---|---|---|---|---|---|---|---|
| Resistance (minimum, Rmin) | Rmin | 0.003 |  |  | Ω | at 23 °C | 1 |
| Resistance after trip (maximum, R1max) | R1max |  |  | 0.024 | Ω | at 23 °C | 1 |
| Maximum current (Imax) | Imax |  |  | 50 | A |  | 1 |
| Maximum time to trip |  |  |  | 5 | s | at 8 A test current | 1 |
| Operating temperature |  | -40 |  | 85 | °C |  | 1 |
| Storage temperature before opening |  |  |  | 40 | °C | Before opening, 70 % RH max | 1 |
| Passive aging resistance change (typical) |  | -10 |  | 10 | % | +85 °C, 1000 hours | 1 |
| Humidity aging resistance change (typical) |  | -15 |  | 15 | % | +85 °C, 85 % R.H., 100 hours | 1 |
| Thermal shock resistance change (typical) |  | -30 |  | 30 | % | -40 °C to +85 °C, 20 times | 1 |
| Hold current | Ihold |  | 3 |  | A | at 23 °C | 1 |
| Trip current | Itrip |  | 6 |  | A | at 23 °C | 1 |
| Tripped power dissipation |  |  | 1 |  | W | at 23 °C | 1 |
| Ihold derating at ambient -40 °C | Ihold |  | 4.41 |  | A | Ambient operating temperature -40 °C | 3 |
| Ihold derating at ambient -20 °C | Ihold |  | 3.99 |  | A | Ambient operating temperature -20 °C | 3 |
| Ihold derating at ambient 0 °C | Ihold |  | 3.54 |  | A | Ambient operating temperature 0 °C | 3 |
| Ihold derating at ambient 23 °C | Ihold |  | 3 |  | A | Ambient operating temperature 23 °C | 3 |
| Ihold derating at ambient 40 °C | Ihold |  | 2.55 |  | A | Ambient operating temperature 40 °C | 3 |
| Ihold derating at ambient 50 °C | Ihold |  | 2.32 |  | A | Ambient operating temperature 50 °C | 3 |
| Ihold derating at ambient 60 °C | Ihold |  | 2.13 |  | A | Ambient operating temperature 60 °C | 3 |
| Ihold derating at ambient 70 °C | Ihold |  | 1.71 |  | A | Ambient operating temperature 70 °C | 3 |
| Ihold derating at ambient 85 °C | Ihold |  | 1.38 |  | A | Ambient operating temperature 85 °C | 3 |

## CAD (KiCad official)

- Symbol: `MF-NSML300`
- Footprint: `Fuse:Fuse_1206_3216Metric`
- 3D model: 1206 (KiCad packages3D, STEP)
- 3D model files: `mf-nsml300-etched.step` / `mf-nsml300-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mf-nsml300.step` / `mf-nsml300.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [BOURNS datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8589943148488126464) (7 pp, sha256 `c44e1bc5ca268455`, 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/mf-nsml300-datasheet.pdf)