# MMBTA55LT1G

**onsemi** · Bipolar (BJT) · SOT-23

MMBTA55LT1G from onsemi, 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 | BASE | input | Base terminal of the PNP driver transistor; the datasheet gives no separate base-current limit, so the absolute limits are the shared ratings of VEBO -4.0 Vdc and IC -500 mAdc. |
| 2 | EMITTER | passive | Emitter terminal of the PNP transistor; emitter-base breakdown is specified at VEBO -4.0 Vdc minimum magnitude and the maximum continuous collector current is -500 mAdc. |
| 3 | COLLECTOR | passive | Collector terminal of the PNP transistor, rated for VCEO -60 Vdc (MMBTA55) and VCBO -60 Vdc, with continuous collector current limited to -500 mAdc. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | onsemi |
| 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−Emitter Voltage (MMBTA55) | VCEO |  |  | -60 | Vdc |  | 1 |
| Collector−Base Voltage (MMBTA55) | VCBO |  |  | -60 | Vdc |  | 1 |
| Emitter−Base Voltage | VEBO |  |  | -4 | Vdc |  | 1 |
| Collector Current − Continuous | IC |  |  | -500 | mAdc |  | 1 |
| Junction and Storage Temperature | TJ, Tstg | -55 |  | 150 | °C |  | 1 |
| Total Device Dissipation FR−5 Board | PD |  |  | 225 | mW | TA = 25°C (FR−5 board, Note 1) | 1 |
| Thermal Resistance, Junction−to−Ambient FR−5 Board | RJA |  |  | 556 | °C/W |  | 1 |
| Total Device Dissipation Alumina Substrate | PD |  |  | 300 | mW | TA = 25°C (alumina substrate, Note 2) | 1 |
| Thermal Resistance, Junction−to−Ambient Alumina Substrate | RJA |  |  | 417 | °C/W |  | 1 |
| Collector−Emitter Breakdown Voltage (MMBTA55) | V(BR)CEO | -60 |  |  | Vdc | IC = −1.0 mAdc, IB = 0 | 2 |
| Emitter−Base Breakdown Voltage | V(BR)EBO | -4 |  |  | Vdc | IE = −100 Adc, IC = 0 | 2 |
| Collector Cutoff Current (VCE) | ICES |  |  | -0.1 | Adc | VCE = −60 Vdc, IB = 0 | 2 |
| Collector Cutoff Current (MMBTA55) | ICBO |  |  | -0.1 | Adc | VCB = −60 Vdc, IE = 0 | 2 |
| DC Current Gain | hFE | 100 |  |  |  | IC = −10 mAdc, VCE = −1.0 Vdc | 2 |
| Collector−Emitter Saturation Voltage | VCE(sat) |  |  | -0.25 | Vdc | IC = −100 mAdc, IB = −10 mAdc | 2 |
| Base−Emitter On Voltage | VBE(on) |  |  | -1.2 | Vdc | IC = −100 mAdc, VCE = −1.0 Vdc | 2 |
| Current−Gain − Bandwidth Product | fT | 50 |  |  | MHz | IC = −100 mAdc, VCE = −1.0 Vdc, f = 100 MHz | 2 |

## CAD (KiCad official)

- Symbol: `MMBTA55LT1G`
- Footprint: `Package_TO_SOT_SMD:SOT-23`
- 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files: `mmbta55lt1g-etched.step` / `mmbta55lt1g-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mmbta55lt1g.step` / `mmbta55lt1g.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [onsemi datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8588905273063194624) (5 pp, sha256 `881203b18108eb32`, 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/mmbta55lt1g-datasheet.pdf)