LM321MFX from Texas Instruments, in a SOT-23-5. 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	+IN	input	Non-inverting input of the op-amp. Input common-mode range includes ground; either input may go up to +32 V without damage.
2	V-	power_in	Negative supply / ground. In single-supply operation, tie to GND. Total supply voltage (V+ - V-) must not exceed 32 V.
3	-IN	input	Inverting input of the op-amp. Input common-mode range includes ground; either input may go up to +32 V without damage.
4	OUTPUT	output	Op-amp output. Sources up to ~40 mA and sinks up to ~20 mA. Short-circuit protected to GND (continuous when V+ ≤ 15 V, TA = 25°C). Stable with high capacitive loads.
5	V+	power_in	Positive supply. Operating range +3 V to +30 V (absolute max 32 V). Supply current typically 430 µA at 5 V, no load.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	SOT-23-5
Category	Op-amp/Cmp
Pins	5

Ordering variants

Same part, different packaging or reel option.

LM321MFX

CAD (KiCad official)

Symbol: LM321MFX
Footprint: Package_TO_SOT_SMD:SOT-23-5
3D model: SOT-23-5 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`lm321mfx.step`	85 KB	You want the bare part, or you mark your own boards.
`lm321mfx-etched.step`	1.3 MB	You want the part with `LM321MFX` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 339 faces against 102 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: Texas Instruments datasheet (16 pp, sha256 9c21ba387dae8e4b, 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