CJ431K from Changjing, 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. Internally compared to the 2.5V bandgap reference (Vref = 2.470-2.520 V typ). Drives the shunt element on when REF exceeds Vref. Reference input current is ~1.5 µA typ (4 µA max).
2	CATHODE	passive	Cathode (K) of the shunt regulator. Sinks 1-100 mA in the on state; VKA max 37 V, IKA range −100 to +150 mA. Off-state cathode current is 0.5 µA max at VKA = 40 V, Vref = 0.
3	ANODE	passive	Anode (A) of the shunt regulator, connected to the low-side / ground return of the shunt current path.

Key specifications

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

Ordering variants

Same part, different packaging or reel option.

CJ431KK

CAD (KiCad official)

Symbol: CJ431K
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
`cj431k.step`	59 KB	You want the bare part, or you mark your own boards.
`cj431k-etched.step`	1.1 MB	You want the part with `CJ431K` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 276 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: Changjing datasheet (6 pp, sha256 f02682f21931ad72, 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