Single general-purpose comparator with an open-collector output, in a SOT-23-5. It compares the two inputs and pulls OUT low when IN- is above IN+; the open-collector stage needs a pull-up so the output can swing to any rail up to the supply, which makes level shifting and wired-OR easy. A wide 5 to 30 V supply range suits it to higher-voltage industrial thresholds where low-voltage comparators cannot reach. The single-channel member of the LM393/339 family lineage.

Pinout

Pin	Name	Type	Function
1	VIN-	input	Inverting analog input of the comparator. Common-mode range 0 V to VS - 1.5 V; must not go more than 0.3 V below the negative rail. Input bias current typ 10 nA, offset current typ 1.6 nA.
2	GND	power_in	Ground / negative supply return. In single-supply operation tied to 0 V; in split-supply operation tied to the negative rail.
3	VIN+	input	Noninverting analog input of the comparator. Common-mode range 0 V to VS - 1.5 V; must not go more than 0.3 V below the negative rail.
4	OUTPUT	output	Open-collector comparator output. Requires an external pull-up resistor to the desired logic rail (e.g., 5.1 kΩ to 5 V typical). Output sink current typ 13 mA (min 6 mA); leakage typ 0.1 nA at VO = 5 V, 1 µA max at VO = 30 V. VOL typ 180 mV at IO = -4 mA.
5	VS	power_in	Positive supply pin. Single-supply range 5 V to 30 V (or ±15 V split). Supply current typ 250 µA at VS = 5 V, typ 300 µA at VS = 30 V.

Key specifications

Parameter	Value
Type	Single comparator (open-collector output)
Supply	5-30 V (single) or +/-15 V
Output	Open collector (needs pull-up)
Input offset	5 mV (typ)
Response time	~1.3 us
Package	SOT-23-5

Ordering variants

Same part, different packaging or reel option.

LM397MFX (SOT-23-5)
LM397MF (SOT-23-5, tube)

CAD (KiCad official)

Symbol: Comparator:LM397 (KiCad official)
Footprint: Package_TO_SOT_SMD:SOT-23-5
3D model: SOT-23-5 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Texas Instruments datasheet (19 pp, sha256 c7a1f660266357ba, 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