# SS8550D331

**ALJ** · Bipolar (BJT) · TO-92

SS8550D331 from ALJ, in a TO-92. 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 | Emitter | passive | Emitter terminal of this PNP transistor, with emitter-base breakdown voltage V(BR)EBO of -5 V at IE = -100µA and maximum emitter-base voltage VEBO of -5 V. |
| 2 | Base | passive | Base terminal of this PNP transistor, which saturates with VBE(sat) of -1.2 V at IC = -800mA and IB = -80mA, with the absolute maximum emitter-base voltage rated at -5 V. |
| 3 | Collector | passive | Collector terminal of this PNP transistor, rated for collector current IC of -1.5 A, collector-base voltage VCBO of -40 V and collector-emitter voltage VCEO of -25 V. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | ALJ |
| Package | TO-92 |
| 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 |  |  | -1.5 | A |  | 1 |
| Junction temperature | Tj |  |  | 150 | °C |  | 1 |
| Storage temperature | Tstg | -55 |  | 150 | °C |  | 1 |
| Collector-base breakdown voltage | V(BR)CBO | -40 |  |  | V | IC = -100µA, IE = 0 | 1 |
| Collector-emitter breakdown voltage | V(BR)CEO | -25 |  |  | V | IC = -1mA, IB = 0 | 1 |
| Emitter-base breakdown voltage | V(BR)EBO | -5 |  |  | V | IE = -100µA, IC = 0 | 1 |
| Collector cut-off current | ICBO |  |  | -100 | nA | VCB = -40V, IE = 0 | 1 |
| Emitter cut-off current | IEBO |  |  | -100 | nA | VEB = -5V, IC = 0 | 1 |
| DC current gain | hFE(1) | 160 |  | 300 |  | VCE = -1V, IC = -100mA | 1 |
| DC current gain | hFE(2) | 40 |  |  |  | VCE = -1V, IC = -800mA | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | -0.5 | V | IC = -800mA, IB = -80mA | 1 |
| Base-emitter saturation voltage | VBE(sat) |  |  | -1.2 | V | IC = -800mA, IB = -80mA | 1 |
| Base-emitter voltage | VBE(on) |  |  | -1 | V | VCE = -1V, IC = -10mA | 1 |
| Out capacitance | Cob |  |  | 20 | pF | VCB = -10V, IE=0mA, f=1MHZ | 1 |
| Transition frequency | fT | 100 |  |  | MHz | VCE =-10V, IC =-50mA,f=30MHz | 1 |

## CAD (KiCad official)

- Symbol: `SS8550D331`
- Footprint: `Package_TO_SOT_THT:TO-92_Inline`
- 3D model: TO-92 (KiCad packages3D, STEP)
- 3D model files: `ss8550d331-etched.step` / `ss8550d331-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ss8550d331.step` / `ss8550d331.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [ALJ datasheet](docs/ss8550d331-datasheet.pdf) (2 pp, sha256 `9b96e9d398f5c521`, retrieved 2026-10-27, 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/ss8550d331-datasheet.pdf)