STWD100NYWY3F from STMicroelectronics, 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	WDO	output	Active-low watchdog output. Asserted low when the internal watchdog timer expires without being cleared. Available as open-drain (requires external pull-up, e.g. 10 kΩ to a supply up to 6 V) or push-pull depending on device suffix.
2	GND	power_in	Device ground reference.
3	EN	input	Active-low chip enable input. When low the watchdog is enabled; when high the watchdog is disabled. Has an internal pull-down to GND, so the device is enabled if EN is left floating. Pulses ≥1 µs are detected; glitches shorter than 100 ns are ignored.
4	WDI	input	Watchdog input. Must be toggled within the watchdog timeout period tWD to clear the internal timer, otherwise WDO is asserted. Low-to-high transitions reset the timer on all versions; high-to-low transitions also reset it on STWD100xW/xX/xY. Pulses ≥1 µs are detected; glitches shorter than 100 ns are ignored.
5	VCC	power_in	Supply voltage input. Watchdog timer starts running once VCC rises above the startup voltage VSTART (~2.2 V). Typical operating current 13 µA.

Key specifications

Parameter	Value
Manufacturer	STMicroelectronics
Package	SOT-23-5
Category	PMIC
Pins	5

Ordering variants

Same part, different packaging or reel option.

STWD100NYWY3FNWWY3F
STWD100NYWY3F
STWD100NYWY3FNPWY3F
STWD100NYWY3FYNWWY3F
STWD100NYWY3FYNYWY3F
STWD100NYWY3FYNPWY3F
STWD100NYWY3FPYW83F

CAD (KiCad official)

Symbol: STWD100NYWY3F
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
`stwd100nywy3f.step`	85 KB	You want the bare part, or you mark your own boards.
`stwd100nywy3f-etched.step`	2.0 MB	You want the part with `STWD100NYWY3F` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 519 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: STMicroelectronics datasheet (25 pp, sha256 19da7a7a2693f2c9, 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