# MMDT5551

**hongjiacheng** · Bipolar (BJT) · SOT-363

MMDT5551 from hongjiacheng, in a SOT-363. 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 | E1 | passive | Emitter of transistor 1 (NPN), per function diagram; VEBO max 6.0 V. |
| 2 | B1 | passive | Base of transistor 1 (NPN), per function diagram; VEBO max 6.0 V. |
| 3 | C2 | passive | Collector of transistor 2 (NPN), per function diagram; VCEO 160 V, VCBO 180 V, IC max 0.2 A. |
| 4 | E2 | passive | Emitter of transistor 2 (NPN), per function diagram; VEBO max 6.0 V. |
| 5 | B2 | passive | Base of transistor 2 (NPN), per function diagram; VEBO max 6.0 V. |
| 6 | C1 | passive | Collector of transistor 1 (NPN), per function diagram; VCEO 160 V, VCBO 180 V, IC max 0.2 A. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | hongjiacheng |
| Package | SOT-363 |
| Category | Transistors/Thyristors |
| Pins | 6 |

## 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 |  |  | 180 | V |  | 1 |
| Collector-Emitter Voltage | VCEO |  |  | 160 | V |  | 1 |
| Emitter-Base Voltage | VEBO |  |  | 6 | V |  | 1 |
| Collector Current | IC |  |  | 0.2 | A |  | 1 |
| Collector Power Dissipation | PC |  |  | 0.2 | W |  | 1 |
| Storage temperature | Tstg | -55 |  | 150 | ℃ |  | 1 |
| Junction temperature | Tj |  |  | 150 | ℃ |  | 1 |
| Transition frequency | fT | 100 |  | 300 | MHz | IC= 10mA, VCE= 10V ,f=100MHz | 1 |
| Collector-Base Breakdown Voltage | V(BR)CBO | 180 |  |  | V | IC=100μA, IE=0 | 2 |
| Collector-Emitter Breakdown Voltage | V(BR)CEO | 160 |  |  | V | IC=1mA, IB=0 | 2 |
| Emitter-Base Breakdown Voltage | V(BR)EBO | 6 |  |  | V | IE=10μA, IC=0 | 2 |
| Collector-Base cut-off current | ICBO |  |  | 50 | nA | VCB=120V,IE=0 | 2 |
| Emitter-Base cut-off current | IEBO |  |  | 50 | nA | VEB= 4.0V,IC=0 | 2 |
| DC Current Gain | hFE(1) | 80 |  |  |  | IC=1mA VCE=5V | 2 |
| DC Current Gain | hFE(2) | 100 |  | 300 |  | IC=10mA VCE= 5V | 2 |
| DC Current Gain | hFE(3) | 30 |  |  |  | IC=50mA VCE=5V | 2 |
| Collector-Emitter Saturation Voltage | VCE(sat) |  |  | 0.15 | V | IC= 10mA IB= 1mA | 2 |
| Collector-Emitter Saturation Voltage | VCE(sat) |  |  | 0.2 | V | IC= 50mA IB= 5mA | 2 |
| Base-Emitter Saturation Voltage | VBE(sat) |  |  | 1 | V | IC= 10mA IB= 1mA | 2 |
| Output Capacitance | Cob |  |  | 6 | pF | VCB= 10V, IE=0, f=1MHZ | 2 |
| Typical Thermal Resistance | RθJ-A |  | 625 |  | ℃/W |  | 1 |

## CAD (KiCad official)

- Symbol: `MMDT5551`
- Footprint: `Package_TO_SOT_SMD:SOT-363_SC-70-6`
- 3D model: SOT-363 (KiCad packages3D, STEP)
- 3D model files: `mmdt5551-etched.step` / `mmdt5551-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mmdt5551.step` / `mmdt5551.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [hongjiacheng datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8564879596571934720) (4 pp, sha256 `8ca3f18eb1da136f`, retrieved 2026-10-09, 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/mmdt5551-datasheet.pdf)