RS821XF 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 swing to within ~20mV of the supply rails with RL=2kΩ; short-circuit current ~110mA typical. Slew rate 10V/us; small-signal bandwidth 14MHz.
2	V-	power_in	Negative supply rail (or ground in single-supply operation). Total supply V+ to V- must be between 2.5V and 5.5V (absolute max 7.0V).
3	+IN	input	Non-inverting input. Rail-to-rail common-mode range (-0.1V to +5.6V with Vs=5.5V). Input bias current ~1pA typical; input terminals are diode-clamped to the supply rails (limit current to ≤10mA).
4	-IN	input	Inverting input. Rail-to-rail common-mode range (-0.1V to +5.6V with Vs=5.5V). Input bias current ~1pA typical; input terminals are diode-clamped to the supply rails (limit current to ≤10mA).
5	V+	power_in	Positive supply rail. Operating range 2.5V to 5.5V (single-supply) or ±1.25V to ±2.75V (dual-supply). Bypass with a 0.1uF capacitor placed close to the 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.

RS821XF
RS821BXF
RS821XK
RS821XM
RS821SXH
RS821SXK
RS822XK
RS822XM
RS822SXN
RS824XP
RS824XQ

CAD (KiCad official)

Symbol: RS821XF
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
`rs821xf.step`	85 KB	You want the bare part, or you mark your own boards.
`rs821xf-etched.step`	1.6 MB	You want the part with `RS821XF` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 385 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 2cea6757d2650c10, 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