# LR123WF220MT4E

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

LR123WF220MT4E 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 | First terminal of the LR12 (2512) metal strip chip resistor; the part is non-polarized and this LR123WF220MT4E is 3W, ±1%, with 220M decoding to 22×10^-4 = 2.2mΩ. |
| 2 | 2 | passive | Second terminal of the LR12 (2512) metal strip chip resistor; the part is non-polarized and interchangeable with the first terminal, with the recommended land pattern for 3mΩ~350mΩ given as a=2.30, b=3.68, i=3.15mm and for 1mΩ/2mΩ as a=3.20, b=3.68, i=1.35mm. |

## 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 | % |  | 2 |
| Temperature coefficient of resistance | TCR | -50 |  | 50 | PPM/℃ | t1=+25°C, t2=125°C | 4 |
| Short-time overload resistance change | ΔR | -0.5 |  | 0.5 | % | LR12-3W: 4 times rated power, 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°C ambient | 4 |
| High temperature exposure resistance change | ΔR | -1 |  | 1 | % | 155±2°C for 1000 H (MIL-STD-202 108A) | 4 |
| Biased humidity resistance change | ΔR | -0.5 |  | 0.5 | % | 1000 hours 85°C/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°C and 30 min at 155°C; 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°C held 10±1 seconds | 4 |
| Solderability coverage |  | 95 |  |  | % | Solder temperature 245±3°C; dwell 2~3 seconds; new, smooth, clean surface | 4 |
| Dielectric withstanding limit surge current |  |  |  | 50 | mA | Applied 500 VAC for 1 minute | 4 |
| Storage temperature (recommended) |  | 15 |  | 35 | ℃ | Warehouse storage recommended by UNI-ROYAL | 6 |
| Storage humidity (recommended) |  | 25 |  | 75 | %RH | Warehouse storage recommended by UNI-ROYAL | 6 |
| Allowed reflow times |  |  |  | 2 | times | Lead-free reflow profile | 5 |
| Peak reflow temperature (recommended) | Tp |  | 260 |  | ℃ | Lead-free reflow profile; time within +0/−5℃ of actual peak 10 seconds | 5 |
| Rated power | P |  | 3 |  | W | Continuous load at ambient 70°C; derate above 70°C per Figure 1 | 4 |

## CAD (KiCad official)

- Symbol: `LR123WF220MT4E`
- Footprint: `Resistor_SMD:R_2512_6332Metric`
- 3D model: 2512 (KiCad packages3D, STEP)
- 3D model files: `lr123wf220mt4e-etched.step` / `lr123wf220mt4e-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lr123wf220mt4e.step` / `lr123wf220mt4e.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/8603235367415783424) (6 pp, sha256 `697e24f2047069dc`, retrieved 2026-10-27, 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/lr123wf220mt4e-datasheet.pdf)