RS331XF from Jiangsu RUNIC Tech, 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	Noninverting comparator input. Common-mode range extends from (V-)-0.1V to (V+)+0.1V; input bias current 1pA typ, 10pA max. Diode-clamped to supply rails - limit external swing beyond rails to ±10mA.
2	V-	power_in	Negative (lowest) power supply pin. Tied to ground for single-supply operation (Vs = 1.8V to 5.5V), or to a negative rail for dual-supply operation (±0.9V to ±2.75V).
3	-IN	input	Inverting comparator input. Common-mode range extends from (V-)-0.1V to (V+)+0.1V; input bias current 1pA typ, 10pA max. Diode-clamped to supply rails - limit external swing beyond rails to ±10mA.
4	OUT	output	Open-drain comparator output. Requires external pull-up resistor (VOH pull-up range up to 5.6V). VSAT ≈150mV typ at IO≤4mA; sink capability 27mA typ at Vs=5V; leakage 0.01nA typ. Output diode-clamped to rails - external signals must stay within ±0.5V of rails and ±55mA.
5	V+	power_in	Positive (highest) power supply pin. Single-supply 1.8V to 5.5V (absolute max 7V vs V-). Bypass locally with 100nF ceramic to V-.

Key specifications

Parameter	Value
Manufacturer	Jiangsu RUNIC Tech
Package	SOT-23-5
Category	Op-amp/Cmp
Pins	5

Ordering variants

Same part, different packaging or reel option.

RS331XF
RS331XFXK
RS331XFXP
RS331XFXQ

CAD (KiCad official)

Symbol: RS331XF
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: Jiangsu RUNIC Tech datasheet (16 pp, sha256 92fbba6bb4adde8a, 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