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Contents

README

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LM431AIM3X

Texas Instruments · Voltage Reference · SOT-23-3

LM431AIM3X from Texas Instruments, in a SOT-23-3. 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 CATHODE passive Cathode / shunt current-and-output pin. Sinks the shunt current (1 mA to 100 mA recommended, 150 mA absolute maximum) from the load; voltage at this pin is regulated to the programmed VZ (VREF up to 37 V absolute maximum). Connects to the external divider whose tap drives the REF pin.
2 REF input Reference input for the internal error amplifier. Compares against the internal 2.495 V bandgap; typical input current 2 uA (4 uA max). Programmed by the external resistor divider between cathode and anode to set the desired cathode regulation voltage VZ = VREF x (1 + R1/R2).
3 ANODE power_in Anode pin, normally connected to circuit ground / return. Forms the common return for the internal shunt current path and the reference divider.

Key specifications

Parameter Value
Manufacturer Texas Instruments
Package SOT-23-3
Category PMIC
Pins 3

Ordering variants

Same part, different packaging or reel option.

  • LM431AIM3X
  • LM431AIM3XCM3X
  • LM431AIM3XCM3
  • LM431AIM3XCM
  • LM431AIM3XIMX
  • LM431AIM3XCMX
  • LM431AIM3XIZ
  • LM431AIM3XCZ
  • LM431AIM3XILP
  • LM431AIM3XCLP

CAD (KiCad official)

  • Symbol: LM431AIM3X
  • Footprint: Package_TO_SOT_SMD:SOT-23-3
  • 3D model: SOT-23-3 (KiCad packages3D, STEP)

Provenance

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

  • Datasheet: Texas Instruments datasheet (38 pp, sha256 a05b3a6ffd35f165, 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