# MMBT5551Q

**Yangzhou Yangjie Elec Tech** · Bipolar (BJT) · SOT-23

MMBT5551Q from Yangzhou Yangjie Elec Tech, 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 NPN transistor; the datasheet gives no base-specific limit apart from VEBO of 6.0 V maximum emitter-base voltage. |
| 2 | E | passive | Emitter of the NPN transistor; VEBO is 6.0 V maximum emitter-base voltage and Tj is 150 °C maximum. |
| 3 | C | passive | Collector of the NPN transistor; VCBO is 180 V, VCEO is 160 V and continuous collector current is 600 mA maximum. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Yangzhou Yangjie Elec Tech |
| 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 breakdown voltage | V(BR)CBO | 180 |  |  | V | IC=100μ A,IE=0 | 2 |
| Collector-emitter breakdown voltage | V(BR)CEO | 160 |  |  | V | IC=1.0mA,IB=0 | 2 |
| Emitter-base breakdown voltage | V(BR)EBO | 6 |  |  | V | IE=10μ A,IC=0 | 2 |
| Collector cut-off current | ICBO |  |  | 50 | nA | VCB=120V, IE=0 | 2 |
| Emitter cut-off current | IEBO |  |  | 50 | nA | VEB=4.0V, IC=0 | 2 |
| DC current gain | hFE | 80 |  |  |  | VCE=5.0V,IC=1.0mA | 2 |
| DC current gain | hFE | 100 |  | 300 |  | VCE=5.0V,IC=10mA | 2 |
| DC current gain | hFE | 50 |  |  |  | VCE=5.0V,IC=50mA | 2 |
| Collector-emitter saturation voltage | VCE(sat) |  |  | 0.2 | V | IC=50mA,IB=5.0mA | 2 |
| Base-emitter saturation voltage | VBE(sat) |  |  | 1 | V | IC=50mA,IB=5.0mA | 2 |
| Transition frequency | fT | 100 |  | 300 | MHz | VCE=5.0Vdc,IC=10mA,f=30MHz | 2 |
| Collector-Base Voltage | VCBO |  |  | 180 | V |  | 1 |
| Collector-Emitter Voltage | VCEO |  |  | 160 | V |  | 1 |
| Emitter-Base Voltage | VEBO |  |  | 6 | V |  | 1 |
| Collector Current -Continuous | IC |  |  | 600 | mA |  | 1 |
| Total Device Dissipation | PD |  |  | 300 | mW | (*) Device mounted on FR-4 PCB 1.0 x 1.0 x 0.06 inch | 1 |
| Thermal Resistance From Junction To Ambient | RθJA |  | 417 |  | ℃/W | (*) Device mounted on FR-4 PCB 1.0 x 1.0 x 0.06 inch | 1 |
| Maximum Junction Temperature | Tj |  |  | 150 | ℃ |  | 1 |
| Storage Temperature | TSTG | -55 |  | 150 | ℃ |  | 1 |

## Materials and finish

As the datasheet states them (page.json `metadata.appearance`; the 3D model's colours follow it).

| Part | Material | Colour / plating | Datasheet says | Page |
|---|---|---|---|---|
| contacts |  | tin | ● Terminals: Tin plated leads, solderable per J-STD-002 and JESD22-B102 | 1 |

## CAD (KiCad official)

- Symbol: `MMBT5551Q`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `mmbt5551q-etched.step` / `mmbt5551q-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mmbt5551q.step` / `mmbt5551q.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Yangzhou Yangjie Elec Tech datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8590235304851234816) (5 pp, sha256 `35e13686bcd993bf`, retrieved 2026-10-18, tier: lcsc)
- **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/mmbt5551q-datasheet.pdf)