LM321-TR from Gainsil, 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. Common-mode input range: -0.1V to (VDD-1.5V). Input bias current typically 45nA.
2	VSS	power_in	Negative supply / ground. Connect to GND for single-supply operation (+3V to +28V on VDD) or to the negative rail (down to -14V) for dual-supply operation.
3	IN-	input	Inverting input of the op-amp. Common-mode input range: -0.1V to (VDD-1.5V). Input bias current typically 45nA.
4	OUT	output	Op-amp output. Output current up to ±40mA typical (60mA max). VOH ≥ 11V and VOL ≤ 20mV with RL = 2kΩ at VS = +14V.
5	VDD	power_in	Positive supply pin. Operating range 3V to 28V single-supply (or up to +14V in dual-supply). Bypass to VSS with a 0.1µF ceramic capacitor close to the pin.

Key specifications

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

Ordering variants

Same part, different packaging or reel option.

LM321-TR
LM321-TRLM358-SR
LM321-TRLM358-MR
LM324-SR

CAD (KiCad official)

Symbol: LM321-TR
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
`lm321-tr.step`	85 KB	You want the bare part, or you mark your own boards.
`lm321-tr-etched.step`	1.3 MB	You want the part with `LM321-TR` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 334 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: Gainsil datasheet (12 pp, sha256 e614f8c2e1c0a60b, 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