RS8551XF 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	OUT	output	Amplifier output. Rail-to-rail output stage; short-circuit current typically 50 mA.
2	V-	power_in	Negative supply pin. Connect to ground for single-supply operation or to the negative rail for dual-supply operation. Total supply (V+ minus V-) must be 2.7 V to 5.5 V (7.0 V absolute maximum).
3	+IN	input	Non-inverting input. Rail-to-rail input common-mode range from (V-)-0.1 V to (V+)+0.1 V. Input bias current 50 pA typical; input terminals are diode-clamped to the supplies.
4	-IN	input	Inverting input. Rail-to-rail input common-mode range from (V-)-0.1 V to (V+)+0.1 V. Input bias current 50 pA typical; input terminals are diode-clamped to the supplies.
5	V+	power_in	Positive supply pin. Operating range +2.7 V to +5.5 V referenced to V- (7.0 V absolute maximum). Place a 0.1 uF decoupling capacitor close to the supply pins.

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.

RS8551XF
RS8551XFXK
RS8551XFXM

CAD (KiCad official)

Symbol: RS8551XF
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
`rs8551xf.step`	85 KB	You want the bare part, or you mark your own boards.
`rs8551xf-etched.step`	1.8 MB	You want the part with `RS8551XF` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 434 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: Jiangsu RUNIC Tech datasheet (14 pp, sha256 6237f5e7f699705d, 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