# LR122WF250LT4E

**UNI-ROYAL(Uniroyal Elec)** · Current Sense Resistors / Shunt Resistors · 2512

LR122WF250LT4E from UNI-ROYAL(Uniroyal Elec), in a 2512. 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 resistor; either orientation. |
| 2 | 2 | passive | Terminal 2 of an unpolarised resistor; either orientation. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | UNI-ROYAL(Uniroyal Elec) |
| Package | 2512 |
| Category | Resistors |
| 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 |
|---|---|---|---|---|---|---|---|
| Temperature coefficient | TCR | -50 |  | 50 | ppm/℃ | R2-R1/(R1×(t2-t1))×10^6; t1 +25℃, t2 125℃ test temperature | 4 |
| Resistance tolerance (F = ±1%) |  | -1 |  | 1 | % | 7th part-number code F = ±1% | 2 |
| Resistance range, LR12 2W | R | 26 |  | 350 | mΩ | LR12 2W, 26~350mΩ range as printed (3~25mΩ also printed for 2W) | 3 |
| Rated power | P |  |  | 2 | W | continuous load at 70℃ ambient; derate above 70℃ per Figure 1 | 3 |
| Solderability, coverage |  | 95 |  |  | % | solder 245±3℃, dwell 2~3 s | 4 |
| Short-time overload, resistance change | ΔR | -0.5 |  | 0.5 | % | LR12-2W: 5× rated power for 5 s | 4 |
| Load life, resistance change | ΔR | -1 |  | 1 | % | 1000 h at rated or max working current (whichever less), 1.5 h ON / 0.5 h OFF, 70±2℃ ambient | 4 |
| High temperature exposure, resistance change | ΔR | -1 |  | 1 | % | 155±2℃ for 1000 h (MIL-STD-202 108A) | 4 |
| Biased humidity, resistance change | ΔR | -0.5 |  | 0.5 | % | 85℃/85%RH, 1000 h, 10% of operating power | 4 |
| Rapid change of temperature, resistance change | ΔR | -0.5 |  | 0.5 | % | 30 min at -55℃ and 30 min at 155℃; 100 cycles | 4 |
| Terminal bending, resistance change | ΔR | -0.5 |  | 0.5 | % | 2 mm, 10 s | 4 |
| Resistance to solder heat, resistance change | ΔR | -0.5 |  | 0.5 | % | 260±5℃ held for 10±1 s | 4 |
| Dielectric withstanding, limit surge current |  |  |  | 50 | mA | applied 500 VAC for 1 minute | 4 |
| Reflow peak temperature | Tp |  |  | 260 | ℃ | Pb-free reflow profile; time within +0/-5℃ of peak 10 s; max 2 reflow passes | 5 |
| Recommended storage temperature |  | 15 |  | 35 | ℃ | warehouse storage recommended by manufacturer | 7 |
| Recommended storage humidity |  | 25 |  | 75 | %RH | warehouse storage recommended by manufacturer | 7 |

## CAD (KiCad official)

- Symbol: `LR122WF250LT4E`
- Footprint: `Resistor_SMD:R_2512_6332Metric`
- 3D model: 2512 (KiCad packages3D, STEP)
- 3D model files: `lr122wf250lt4e-etched.step` / `lr122wf250lt4e-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lr122wf250lt4e.step` / `lr122wf250lt4e.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [UNI-ROYAL(Uniroyal Elec) datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8603144030037962752) (7 pp, sha256 `e01cdf7929676065`, retrieved 2026-10-17, 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/lr122wf250lt4e-datasheet.pdf)