# S8550-MS

**MSKSEMI** · Bipolar (BJT) · SOT-23

S8550-MS from MSKSEMI, 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 | passive | Base terminal of the PNP transistor; the datasheet gives no pin-specific limit, and the device's emitter-base reverse voltage VEBO is rated at -5 V. |
| 2 | EMITTER | passive | Emitter terminal of the PNP transistor; the emitter-base reverse voltage VEBO is rated at -5 V and the emitter-base breakdown is specified at IE = -100 μA. |
| 3 | COLLECTOR | passive | Collector terminal of the PNP transistor, rated for VCBO -40 V, VCEO -25 V and continuous collector current IC -0.5 A. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | MSKSEMI |
| Package | SOT-23 |
| Category | Transistors/Thyristors |
| 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-base voltage | VCBO |  |  | -40 | V |  | 2 |
| Collector-emitter voltage | VCEO |  |  | -25 | V |  | 2 |
| Emitter-base voltage | VEBO |  |  | -5 | V |  | 2 |
| Collector current, continuous | IC |  |  | -0.5 | A |  | 2 |
| Collector dissipation | PC |  |  | 0.3 | W |  | 2 |
| Junction temperature | Tj |  |  | 150 | ℃ |  | 2 |
| Storage temperature | Tstg | -55 |  | 150 | ℃ |  | 2 |
| Collector-base breakdown voltage | V(BR)CBO | -40 |  |  | V | IC = -100μA, IE=0 | 2 |
| Collector-emitter breakdown voltage | V(BR)CEO | -25 |  |  | V | IC =-1mA, IB=0 | 2 |
| Emitter-base breakdown voltage | V(BR)EBO | -5 |  |  | V | IE= -100μA, IC=0 | 2 |
| Collector cut-off current (ICBO) | ICBO |  |  | -0.1 | μA | VCB= -40V, IE=0 | 2 |
| Collector cut-off current (ICEO) | ICEO |  |  | -0.1 | μA | VCE= -20V, IB=0 | 2 |
| Emitter cut-off current | IEBO |  |  | -0.1 | μA | VEB= -3V, IC=0 | 2 |
| DC current gain, rank range | hFE(1) | 120 |  | 400 |  | VCE= -1V, IC= -50mA | 2 |
| DC current gain | hFE(2) | 50 |  |  |  | VCE= -1V, IC= -500mA | 2 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | -0.6 | V | IC=-500mA, IB= -50mA | 2 |
| Base-emitter saturation voltage | VBE(sat) |  |  | -1.2 | V | IC=-500mA, IB= -50mA | 2 |
| Transition frequency | fT | 150 |  |  | MHz | VCE= -6V, IC= -20mA, f=30MHz | 2 |

## CAD (KiCad official)

- Symbol: `S8550-MS`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `s8550-ms-etched.step` / `s8550-ms-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `s8550-ms.step` / `s8550-ms.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [MSKSEMI datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8590237005360758784) (5 pp, sha256 `25a6b4218419c87e`, retrieved 2026-10-19, tier: lcsc)
- **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/s8550-ms-datasheet.pdf)