# LGS7381

**Legend Si** · Battery Management · SOT-23-5

LGS7381 from Legend Si, in a SOT-23-5. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | CE | input | Enable input pin; high level enables charging, low level disables charging; connect to VCC or MCU control. |
| 2 | GND | power_in | Chip ground reference. |
| 3 | BAT | output | Battery charging output pin; connect to battery positive terminal with at least 10μF ceramic capacitor to ground. |
| 4 | VCC | power_in | Power supply input pin with recommended operating voltage 4.5V to 6V; bypass to ground with at least 10μF ceramic capacitor placed close to pin. |
| 5 | PROG | output | Charging current setting and monitoring output pin; pin voltage fixed at 0.05V (SC), 0.1V (TC), or 1V (CC) depending on charging mode; external 1% resistor to ground sets current via IBAT = (VPROG / RPROG) × 1000. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Legend Si |
| Package | SOT-23-5 |
| Category | Power Management (PMIC) |
| Pins | 5 |

## CAD (KiCad official)

- Symbol: `LGS7381`
- Footprint: `Package_TO_SOT_SMD:SOT-23-5`
- 3D model: SOT-23-5 (KiCad packages3D, STEP)
- 3D model files: `lgs7381-etched.step` / `lgs7381-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lgs7381.step` / `lgs7381.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Legend Si datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8756398856626561024) (11 pp, sha256 `630ea8fc9f8f8ca1`, retrieved 2026-09-22, tier: lcsc)
- **Datasheet language:** Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.2`, primary `claude-haiku-4-5-20251001` (text), consensus `claude-sonnet-4-6` (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/lgs7381-datasheet.pdf)