# MPSA42SI

**YFW** · Bipolar (BJT) · SOT-89

MPSA42SI from YFW, in a SOT-89. 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 terminal of the NPN transistor, with emitter-base voltage rated at VEBO 5 V maximum and emitter-base breakdown V(BR)EBO of 5 V minimum. |
| 2 | Collector | passive | Collector terminal of the NPN transistor, rated at VCBO 300 V and VCEO 300 V with collector current IC 0.3 A continuous. |
| 3 | Emitter | passive | Emitter terminal of the NPN transistor, the reference for the VCEO 300 V and VEBO 5 V ratings. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | YFW |
| Package | SOT-89 |
| 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 |  |  | 300 | V |  | 1 |
| Collector-Emitter Voltage | VCEO |  |  | 300 | V |  | 1 |
| Emitter-Base Voltage | VEBO |  |  | 5 | V |  | 1 |
| Collector Current - Continuous | IC |  |  | 0.3 | A |  | 1 |
| Collector Power dissipation | PC |  |  | 0.35 | W |  | 1 |
| Thermal Resistance, junction to Ambient | RθJA |  |  | 357 | °C/mW |  | 1 |
| Junction Temperature | TJ |  |  | 150 | °C |  | 1 |
| Storage Temperature | TSTG | -55 |  | 150 | °C |  | 1 |
| Collector-base breakdown voltage | V(BR)CBO | 300 |  |  | V | IC= 100μA, IE=0 | 1 |
| Collector-emitter breakdown voltage | V(BR)CEO | 300 |  |  | 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 |  |  | 0.25 | μA | VCB=200V, IE=0 | 1 |
| Emitter cut-off current | IEBO |  |  | 0.1 | μA | VEB= 5V, IC=0 | 1 |
| DC current gain hFE(1) | hFE(1) | 60 |  |  |  | VCE= 10V, IC= 1mA | 1 |
| DC current gain hFE(2) | hFE(2) | 100 |  | 200 |  | VCE= 10V, IC= 10mA | 1 |
| DC current gain hFE(3) | hFE(3) | 60 |  |  |  | VCE= 10V, IC= 10mA | 1 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 0.2 | V | IC=20mA, IB= 2mA | 1 |
| Base-emitter saturation voltage | VBE(sat) |  |  | 0.9 | V | IC= 20mA, IB=2mA | 1 |
| Transition frequency | fT | 50 |  |  | MHz | VCE= 20V, IC= 10mA, f=30MHz | 1 |

## CAD (KiCad official)

- Symbol: `MPSA42SI`
- Footprint: `Package_TO_SOT_SMD:SOT-89-3`
- 3D model: SOT-89 (KiCad packages3D, STEP)
- 3D model files: `mpsa42si-etched.step` / `mpsa42si-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mpsa42si.step` / `mpsa42si.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [YFW datasheet](docs/mpsa42si-datasheet.pdf) (4 pp, sha256 `47e504a3a44ed616`, retrieved 2026-10-18, 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/mpsa42si-datasheet.pdf)