# LGS5500EP

**Legend Si** · Battery Management · ESOP-8

LGS5500EP from Legend Si, in a ESOP-8. 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 | ISET | passive | Battery charge-current preset pin; connect an external 1% resistor (≤14kΩ sets 400mA, 20kΩ 600mA, 27kΩ 800mA, ≥36kΩ or open 1000mA). |
| 2 | VIN | power_in | Charger input, recommended 4.5V to 5.5V with 20V absolute maximum and 7V input overvoltage protection; place a 10µF or larger ceramic bypass capacitor as close as possible between VIN and GND. |
| 3 | VL | bidirectional | Charge output pin connected to the battery positive terminal; place at least a 10µF ceramic capacitor on this pin. |
| 4 | LX | passive | Internal power switch node for the boost converter; connect the power inductor (2.2µH to 10µH, 2.2µH recommended) and the output here. |
| 5 | VH | power_out | Boost discharge output, default 5V; place at least a 20µF capacitor to GND. |
| 6 | NC | unconnected | Test pin; leave floating. |
| 7 | VSET (LED) | bidirectional | Time-multiplexed pin: LED charge-indicator output that goes high when lit (2mA LED drive with external series resistor), and battery charge-voltage preset input VSET, set by an external 1% resistor (≤14kΩ 4.20V, 20kΩ 4.30V, 27kΩ 4.35V, ≥36kΩ or open 4.40V). |
| 8 | NTC | input | Battery temperature sense input; the NTC function is enabled when the pin voltage exceeds 4%VIN and is disabled if the pin is floating or grounded. |
| 9 | EP | passive | Exposed pad (from the footprint; not named in the datasheet pin table). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Legend Si |
| Package | ESOP-8 |
| Category | Power Management (PMIC) |
| Pins | 9 |

## CAD (KiCad official)

- Symbol: `LGS5500EP`
- Footprint: `Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.41x3.3mm`
- 3D model: ESOP-8 (KiCad packages3D, STEP)
- 3D model files: `lgs5500ep-etched.step` / `lgs5500ep-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lgs5500ep.step` / `lgs5500ep.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/8755875379959468032) (12 pp, sha256 `e31831e8e286365c`, retrieved 2026-10-09, 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 0.3`, primary `claude-haiku-5-5` (text), consensus `claude-sonnet-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/lgs5500ep-datasheet.pdf)