# KIA431AF-RTF

**KEC Semicon** · Voltage Reference · SOT-89-3

KIA431AF-RTF from KEC Semicon, 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 | REF | input | Reference input. High-impedance input to the internal error amplifier that is compared against the 2.495 V bandgap. Typically tied to the tap of an external R1/R2 divider from cathode to anode to program Vka = Vref x (1 + R1/R2) + Iref x R1. Input current 1.8 uA typ, 4.0 uA max at 25 C. |
| 2 | A | power_in | Anode. Common/ground-side terminal of the shunt regulator; the internal reference and error amp are referenced to this pin. For SOT-89 the heat sink tab is electrically common to pin 2 (Anode). |
| 3 | K | power_in | Cathode. Regulated shunt output; sinks current through an external series resistor from the supply to hold Vka at the programmed value. Absolute max Vka = 37 V; continuous cathode current range -100 to +150 mA; minimum cathode current for regulation 0.5 mA typ (1.0 mA max). |

## Key specifications

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

## Ordering variants

Same part, different packaging or reel option.

- `KIA431AF-RTFF`
- `KIA431AF-RTFZF`
- `KIA431AF-RTF`
- `KIA431AF-RTFBF`
- `KIA431AF-RTF(blank)`
- `KIA431AF-RTFZ`
- `KIA431AF-RTFA`
- `KIA431AF-RTFB`
- `KIA431AF-RTFM`
- `KIA431AF-RTFZM`
- `KIA431AF-RTFAM`
- `KIA431AF-RTFBM`

## CAD (KiCad official)

- Symbol: `KIA431AF-RTF`
- Footprint: `Package_TO_SOT_SMD:SOT-89-3`
- 3D model: SOT-89-3 (KiCad packages3D, STEP)
- 3D model files: `kia431af-rtf-etched.step` / `kia431af-rtf-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `kia431af-rtf.step` / `kia431af-rtf.glb` are the bare package body.

## 3D model downloads

Two STEP files. Same geometry, different body top:

| File | Size | Use it when |
|---|---|---|
| [`kia431af-rtf.step`](kia431af-rtf.step) | 57 KB | You want the bare part, or you mark your own boards. |
| [`kia431af-rtf-etched.step`](kia431af-rtf-etched.step) | 1.3 MB | You want the part with `KIA431AF-RTF` already on it. |

The marking in the etched file is real recessed geometry cut into the solid, not a
texture or a decal: 371 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:** [KEC Semicon datasheet](docs/kia431af-rtf-datasheet.pdf) (7 pp, sha256 `b0b1ac14e62a5a3f`, retrieved 2026-08-17, tier: lcsc)
- **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/kia431af-rtf-datasheet.pdf)