LR431ATLT1G 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. Sense pin compared internally to the 2.495 V bandgap reference; drives the internal amplifier that controls the cathode shunt current. Typical reference input current 1.5 µA (Iref).
2	K	passive	Cathode. Shunt-regulator output terminal; sinks 1-100 mA in regulation with Vka ranging from Vref (~2.495 V) up to 36 V max. Off-state cathode current is 0.05 µA typ at Vka = 36 V, Vref = 0.
3	A	passive	Anode. Reference-side ground return for the shunt element; connects to the low side of the load and to the R1/R2 divider common node.

Key specifications

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

Ordering variants

Same part, different packaging or reel option.

LR431ATLT1G
LR431BTLT1G
LR431APTLT1G
LR431BPTLT1G
LR431ALT1G
LR431BLT1G
LR431APLT1G
LR431BPLT1G

CAD (KiCad official)

Symbol: LR431ATLT1G
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
`lr431atlt1g.step`	59 KB	You want the bare part, or you mark your own boards.
`lr431atlt1g-etched.step`	1.4 MB	You want the part with `LR431ATLT1G` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 381 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 889e59d6aba7b3a0, 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