# L78L12ABUTR

**STMicroelectronics** · Voltage Regulators - Linear, Low Drop Out (LDO) Regulators · SOT-89-3

L78L12ABUTR from STMicroelectronics, in a SOT-89-3. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VOUT | power_out | Regulated +12 V output. Deliver up to 100 mA. Recommended output decoupling capacitor 0.1 µF to GND for stability and transient response. |
| 2 | GND | power_in | Common ground / reference return. On SOT-89 this is the large center pad, tied to the die attach flag for thermal dissipation, so bond to a copper pour for heat-sinking. |
| 3 | VIN | power_in | Unregulated DC input. Absolute maximum 35 V (for 12-15 V output variants). Recommended input decoupling capacitor 0.33 µF placed close to the pin. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | STMicroelectronics |
| Package | SOT-89-3 |
| Category | PMIC |
| Pins | 3 |

## Ordering variants

Same part, different packaging or reel option.

- `L78L12ABUTR`
- `L78L12ACUTR`
- `L78L12ABZ`
- `L78L12ACZ`
- `L78L12ABZ-AP`
- `L78L12ACZ-AP`
- `L78L12ACZ-TR`
- `L78L12ABD-TR`
- `L78L12ACD13TR`
- `L78L12CD13TR`

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Output voltage (TJ = 25 °C) | VO | 11.5 | 12 | 12.5 | V | TJ = 25 °C | 21 |
| Output voltage | VO | 11.4 |  | 12.6 | V | IO = 1 to 40 mA, VI = 14.5 to 27 V | 21 |
| Supply voltage rejection | SVR | 37 | 42 |  | dB | VI = 15 to 25 V, f = 120 Hz, IO = 40 mA, TJ = 25 °C | 21 |
| Absolute maximum DC input voltage | VI |  |  | 35 | V | VO = 12 to 15 V | 5 |
| Output current | IO |  |  | 100 | mA |  | 5 |
| Storage temperature range | TSTG | -65 |  | 150 | °C |  | 5 |
| Operating junction temperature range | TOP | -40 |  | 125 | °C | for L78LxxAB | 5 |
| Thermal resistance junction-ambient (SOT-89) | RthJA |  |  | 55 | °C/W | Considering 6 cm² copper board heat-sink | 5 |
| Line regulation | ∆VO |  | 250 |  | mV | VI = 14.5 to 27 V, TJ = 25 °C | 21 |
| Line regulation | ∆VO |  | 200 |  | mV | VI = 16 to 27 V, TJ = 25 °C | 21 |
| Load regulation | ∆VO |  | 100 |  | mV | IO = 1 to 100 mA, TJ = 25 °C | 21 |
| Load regulation | ∆VO |  | 50 |  | mV | IO = 1 to 40 mA, TJ = 25 °C | 21 |
| Quiescent current | Id |  | 6.5 |  | mA | TJ = 25 °C | 21 |
| Quiescent current | Id |  | 6 |  | mA | TJ = 125 °C | 21 |
| Quiescent current change | ∆Id |  | 0.1 |  | mA | IO = 1 to 40 mA | 21 |
| Quiescent current change | ∆Id |  | 1.5 |  | mA | VI = 16 to 27 V | 21 |
| Output noise voltage | eN |  | 80 |  | µV | B = 10 Hz to 100 kHz, TJ = 25 °C | 21 |
| Dropout voltage | Vd |  | 1.7 |  | V |  | 21 |

## CAD (KiCad official)

- Symbol: `L78L12ABUTR`
- Footprint: `Package_TO_SOT_SMD:SOT-89-3`
- 3D model: SOT-89-3 (KiCad packages3D, STEP)
- 3D model files: `l78l12abutr-etched.step` / `l78l12abutr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `l78l12abutr.step` / `l78l12abutr.glb` are the bare package body.

## 3D model downloads

Two STEP files. Same geometry, different body top:

| File | Size | Use it when |
|---|---|---|
| [`l78l12abutr.step`](l78l12abutr.step) | 57 KB | You want the bare part, or you mark your own boards. |
| [`l78l12abutr-etched.step`](l78l12abutr-etched.step) | 1.4 MB | You want the part with `L78L12ABUTR` already on it. |

The marking in the etched file is real recessed geometry cut into the solid, not a
texture or a decal: 377 faces against 42 in the bare model. It
survives export, section views, and rendering in any CAD tool, and it drops straight
into KiCad or Fusion with no extra setup.

## Provenance

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

- **Datasheet:** [STMicroelectronics datasheet](https://www.st.com/resource/en/datasheet/l78l12abutr.pdf) (45 pp, sha256 `43922ae159face7e`, retrieved 2026-08-17, tier: manufacturer)
- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/l78l12abutr-datasheet.pdf)