LR431APTLT1G from LRC, in a SOT-23. 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 sense input to the internal 2.5 V bandgap comparator. Connect to the mid-point of the external R1/R2 divider between cathode and anode; VKA = Vref × (1 + R1/R2) + Iref × R1. Iref typ 1.5 µA (max 4 µA).
2	K	passive	Cathode. Regulated shunt terminal; sinks 1-100 mA in the stable/regulating region. Absolute max VKA = 36 V, cathode current range -100 to +150 mA. Dynamic impedance ~0.2 Ω (typ) at f ≤ 1 kHz.
3	A	passive	Anode. Common/return terminal of the shunt regulator; normally tied to circuit ground (or to the low side of the sensed rail).

Key specifications

Parameter	Value
Manufacturer	LRC
Package	SOT-23
Category	PMIC
Pins	3

Ordering variants

Same part, different packaging or reel option.

LR431APTLT1G

CAD (KiCad official)

Symbol: LR431APTLT1G
Footprint: Package_TO_SOT_SMD:SOT-23
3D model: SOT-23 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`lr431aptlt1g.step`	59 KB	You want the bare part, or you mark your own boards.
`lr431aptlt1g-etched.step`	1.6 MB	You want the part with `LR431APTLT1G` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 417 faces against 69 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: LRC datasheet (5 pp, sha256 3a6bd98799907b53, 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