# LR123WF270LT4E

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

LR123WF270LT4E 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 | One of two interchangeable metal-strip terminals of the LR12 2512 chip resistor (Sn solder plated), land pad a = 2.30 mm wide by b = 3.68 mm for 3~350 mΩ values. |
| 2 | 2 | passive | Second interchangeable metal-strip terminal of the LR12 2512 chip resistor (Sn solder plated), land pad a = 2.30 mm wide by b = 3.68 mm with i = 3.15 mm gap between pads for 3~350 mΩ values. |

## 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 |
|---|---|---|---|---|---|---|---|
| Resistance tolerance |  | -1 |  | 1 | % | F=±1% (7th code of MPN) | 2 |
| Temperature coefficient of resistance |  | -50 |  | 50 | PPM/℃ | t1 +25℃, t2 125℃ (test temperature) | 4 |
| Rated power |  |  |  | 3 | W | 3W type; continuous load at ambient 70℃, derate above 70℃ per Figure 1 | 2 |
| Short-time overload resistance change | ΔR | -0.5 |  | 0.5 | % | 4 times rated power (LR12-3W), 5 seconds | 4 |
| Load life resistance change | ΔR | -1 |  | 1 | % | 1000 hours 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 | % | 1000 hours 85℃/85%RH, 10% of operating power; measured at 24±4 hours after test | 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 sec | 4 |
| Resistance to solder heat resistance change | ΔR | -0.5 |  | 0.5 | % | Dip at 260±5℃ for 10±1 seconds | 4 |
| Dielectric withstanding surge current limit |  |  |  | 50 | mA | 500 VAC applied for 1 minute; limit surge current 50 mA (max.) | 4 |
| Storage temperature (recommended) |  | 15 |  | 35 | ℃ | Recommended warehouse storage condition | 6 |
| Storage humidity (recommended) |  | 25 |  | 75 | %RH | Recommended warehouse storage condition | 6 |
| Rated ambient temperature |  |  | 70 |  | ℃ | Power rating based on continuous load at this ambient; derate above per Figure 1 | 4 |

## CAD (KiCad official)

- Symbol: `LR123WF270LT4E`
- Footprint: `Resistor_SMD:R_2512_6332Metric`
- 3D model: 2512 (KiCad packages3D, STEP)
- 3D model files: `lr123wf270lt4e-etched.step` / `lr123wf270lt4e-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lr123wf270lt4e.step` / `lr123wf270lt4e.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/8603235368296857600) (6 pp, sha256 `697e24f2047069dc`, retrieved 2026-11-05, 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/lr123wf270lt4e-datasheet.pdf)