WAS3157B-6 from WILLSEMI Will Semicon, in a SOT-363. 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	B1	bidirectional	Data 1 terminal (analog switch throw). Normally open; connected to A when SEL is high. Bidirectional analog signal, 0 to VCC operating range; absolute max -0.5V to 6.5V. Continuous current ±50mA.
2	GND	power_in	Ground reference for the device.
3	B0	bidirectional	Data 0 terminal (analog switch throw). Normally closed; connected to A when SEL is low. Bidirectional analog signal, 0 to VCC operating range; absolute max -0.5V to 6.5V. Continuous current ±50mA.
4	A	bidirectional	Common data terminal (SPDT pole). Connects to B0 or B1 according to SEL logic. Bidirectional analog signal, 0 to VCC operating range; absolute max -0.5V to 6.5V. Continuous current ±50mA. A-port on-capacitance ~18.5pF.
5	VCC	power_in	Positive supply input. Recommended operating range 2.3V to 5.5V; absolute max -0.5V to 6.5V. Quiescent current <1uA typical.
6	SEL	input	Digital switch select input. Logic low → B0 connected to A; logic high → B1 connected to A. Overvoltage-tolerant up to 7.0V regardless of VCC. VIH ≥ 1.5V (VCC=3.6~~4.5V) or ≥ 1.3V (VCC=2.3~~3.6V); VIL ≤ 0.6V or 0.4V respectively. Input capacitance ~5.5pF.

Key specifications

Parameter	Value
Manufacturer	WILLSEMI Will Semicon
Package	SOT-363
Category	Interface
Pins	6

Ordering variants

Same part, different packaging or reel option.

WAS3157B-6/TR

CAD (KiCad official)

Symbol: WAS3157B-6
Footprint: Package_TO_SOT_SMD:SOT-363_SC-70-6
3D model: SOT-363 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`was3157b-6.step`	99 KB	You want the bare part, or you mark your own boards.
`was3157b-6-etched.step`	2.0 MB	You want the part with `WAS3157B-6` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 489 faces against 117 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: WILLSEMI Will Semicon datasheet (7 pp, sha256 56e6f7d833c78371, 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