# MMBT431LT1

**ALJ** · Voltage Reference · SOT-89

MMBT431LT1 from ALJ, 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 | REFERENCE | input | Reference input of the adjustable shunt regulator, where Vref is 2.445 to 2.545 V (typ. 2.495 V) at IKA = 10 mA, and Iref is rated 0.05 to 10 mA. |
| 2 | ANODE | passive | Common anode terminal of the shunt regulator, which must carry at least IKA(min) = 0.3 mA for regulation, with the absolute cathode-to-anode limits given in the ratings table. |
| 3 | CATHODE | passive | Cathode terminal whose voltage can be adjusted up to 36 V, with absolute maximum VKA of 37 V and continuous cathode current range of -100 to +150 mA. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | ALJ |
| Package | SOT-89 |
| Category | Power Management (PMIC) |
| 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 |
|---|---|---|---|---|---|---|---|
| Cathode Voltage | VKA |  |  | 37 | V |  | 1 |
| Cathode Current Range (Continuous) | IKA | -100 |  | 150 | mA |  | 1 |
| Reference Input Current Range | Iref | 0.05 |  | 10 | mA |  | 1 |
| Power Dissipation | PD |  |  | 500 | mW |  | 1 |
| Thermal Resistance from Junction to Ambient | RθJA |  |  | 250 | °C/W |  | 1 |
| Operating Junction Temperature | Tj |  |  | 150 | °C |  | 1 |
| Operating Ambient Temperature Range | Topr | -40 |  | 125 | °C |  | 1 |
| Storage temperature Range | Tstg | -65 |  | 150 | °C |  | 1 |
| Reference input voltage | Vref | 2.445 | 2.495 | 2.545 | V | VKA=VREF, IKA=10mA | 2 |
| Deviation of reference input voltage over temperature | △Vref /△T |  | 4.5 | 17 | mV | VKA=VREF, IKA=10mA, Tmin≤Ta≤Tmax | 2 |
| Ratio of change in reference input voltage to change in cathode voltage | △Vref /△VKA |  | -1 | -2.7 | mV/V | IKA=10mA, △VKA=10V~VREF | 2 |
| Ratio of change in reference input voltage to change in cathode voltage | △Vref /△VKA |  | -0.5 | -2 | mV/V | IKA=10mA, △VKA=36V~10V | 2 |
| Reference input current | lref |  | 1.5 | 4 | μA | IKA=10mA, R1=10kΩ, R2=∞ | 2 |
| Deviation of reference input current over full temperature range | △lref /△T |  | 0.4 | 1.2 | μA | lKA=10mA, R1=10kΩ, R2=∞, Ta=full Temperature | 2 |
| Minimum cathode current for regulation | IKA(min) |  |  | 0.3 | mA | VKA=VREF | 2 |
| Off-state cathode Current | IKA(OFF) |  | 0.05 | 0.2 | μA | VKA=36V, VREF=0 | 2 |
| Dynamic impedance | ZKA |  | 0.15 | 0.5 | Ω | VKA=VREF, f≤1.0kHz, IKA=1 to 100mA | 2 |

## CAD (KiCad official)

- Symbol: `MMBT431LT1`
- Footprint: `Package_TO_SOT_SMD:SOT-89-3`
- 3D model: SOT-89 (KiCad packages3D, STEP)
- 3D model files: `mmbt431lt1-etched.step` / `mmbt431lt1-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mmbt431lt1.step` / `mmbt431lt1.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [ALJ datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8603369170746548224) (4 pp, sha256 `2ebed224d662b431`, 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/mmbt431lt1-datasheet.pdf)