# S8550-6AF

**FOSAN** · Bipolar (BJT) · SOT-23

S8550-6AF from FOSAN, 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 | B | input | Base of the PNP transistor; the emitter-base voltage is limited to -5 V (VEBO) and the base-emitter saturation voltage is at most -1.2 V at IC=-500 mA, IB=-50 mA. |
| 2 | E | passive | Emitter of the PNP transistor; the emitter-base breakdown voltage is at least -5 V at IE=-100 uA. |
| 3 | C | passive | Collector of the PNP transistor; VCBO is -40 V, VCEO is -25 V, and continuous IC is -500 mA (ICM -800 mA peak). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | FOSAN |
| 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 |  | 1 |
| Collector-Emitter Voltage | VCEO | -25 |  |  | V |  | 1 |
| Emitter-Base Voltage | VEBO | -5 |  |  | V |  | 1 |
| Collector Current | IC | -500 |  |  | mA |  | 1 |
| Collector Current (peak) | ICM | -800 |  |  | mA |  | 1 |
| Power dissipation | PC |  |  | 300 | mW | Ta=25℃ | 1 |
| Thermal Resistance Junction-Ambient | RΘJA |  |  | 417 | ℃/W |  | 1 |
| Junction and Storage Temperature | TJ,Tstg | -55 |  | 150 | ℃ |  | 1 |
| Collector-Base Breakdown Voltage | BVCBO | -40 |  |  | V | IC= -100uA, IE=0 | 2 |
| Collector-Emitter Breakdown Voltage | BVCEO | -25 |  |  | V | IC= -1mA, IB=0 | 2 |
| Emitter-Base Breakdown Voltage | BVEBO | -5 |  |  | V | IE= -100uA, IC=0 | 2 |
| Collector-Base Leakage Current | ICBO |  |  | -100 | nA | VCB= -40V, IE=0 | 2 |
| Collector-Emitter Punch Through Current | ICES |  |  | -100 | nA | VCE= -20V, VBE=0 | 2 |
| Emitter-Base Leakage Current | IEBO |  |  | -100 | nA | VEB= -5V, IC=0 | 2 |
| DC Current Gain | HFE(1) | 85 |  | 400 |  | VCE= -1V, IC= -100mA | 2 |
| DC Current Gain | HFE(2) | 40 |  |  |  | VCE= -1V, IC= -800mA | 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 |

## CAD (KiCad official)

- Symbol: `S8550-6AF`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `s8550-6af-etched.step` / `s8550-6af-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `s8550-6af.step` / `s8550-6af.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [FOSAN datasheet](docs/s8550-6af-datasheet.pdf) (4 pp, sha256 `fcb6f6174c2fb40f`, retrieved 2026-10-21, 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-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/s8550-6af-datasheet.pdf)