# L8550HQ

**YONGYUTAI** · Bipolar Transistors - BJT · SOT-23

L8550HQ from YONGYUTAI, in a SOT-23. 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 | BASE | input | Base of the PNP transistor; emitter-base voltage limit is -5 V (V(BR)EBO min -5 V at IE=-100µA). |
| 2 | EMITTER | passive | Emitter of the PNP transistor; the datasheet gives the emitter cutoff current as max -150 nA at VEB=-4 V. |
| 3 | COLLECTOR | passive | Collector of the PNP transistor; VCEO is -25 V, VCBO is -40 V and the collector current is -1500 mAdc max. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | YONGYUTAI |
| Package | SOT-23 |
| Category | Triode/MOS Tube/Transistor |
| Pins | 3 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Collector-Emitter Voltage | VCEO |  |  | -25 | V |  | 1 |
| Collector-Base Voltage | VCBO |  |  | -40 | V |  | 1 |
| Emitter-Base Voltage | VEBO |  |  | -5 | V |  | 1 |
| Collector Current | IC |  |  | -1500 | mAdc |  | 1 |
| Total Device Dissipation FR-5 Board | PD |  |  | 225 | mW | FR-5 Board, TA=25°C | 1 |
| Total Device Dissipation Alumina Substrate | PD |  |  | 300 | mW | Alumina Substrate, TA=25°C | 1 |
| Thermal Resistance, Junction to Ambient (FR-5) | RθJA |  |  | 556 | °C/W | FR-5 Board | 1 |
| Thermal Resistance, Junction to Ambient (Alumina) | RθJA |  |  | 417 | °C/W | Alumina Substrate | 1 |
| Junction and Storage Temperature | Tj,Tstg | -55 |  | 150 | °C |  | 1 |
| Collector-Emitter Breakdown Voltage | V(BR)CEO | -25 |  |  | V | IC=-1.0mA | 2 |
| Emitter-Base Breakdown Voltage | V(BR)EBO | -5 |  |  | V | IE=-100µA | 2 |
| Collector-Base Breakdown Voltage | V(BR)CBO | -40 |  |  | V | IC=-100µA | 2 |
| Collector Cutoff Current | ICBO |  |  | -150 | nA | VCB=-35V | 2 |
| Emitter Cutoff Current | IEBO |  |  | -150 | nA | VEB=-4V | 2 |
| DC Current Gain | HFE | 150 |  | 300 |  | IC=-100mA,VCE=-1V | 2 |
| Collector-Emitter Saturation Voltage | VCE(S) |  |  | -0.5 | V | IC=-800mA,IB=-80mA | 2 |

## CAD (KiCad official)

- Symbol: `L8550HQ`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `l8550hq-etched.step` / `l8550hq-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `l8550hq.step` / `l8550hq.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [YONGYUTAI datasheet](docs/l8550hq-datasheet.pdf) (3 pp, sha256 `922f9786c0042b2b`, retrieved 2026-10-22, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-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/l8550hq-datasheet.pdf)