SSP9451 from Shanghai Siproin Microelectronics, in a SOT-23-6. 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	BST	passive	Bootstrap. Positive supply for the internal floating high-side MOSFET driver. Connect a bypass capacitor between this pin and SW; the internal bootstrap regulator holds this rail ~5V above SW (BST-to-SW absolute max 6.0V).
2	GND	power_in	Ground return. Should be connected as close as possible to the output capacitor to avoid high-current switching paths.
3	FB	input	Feedback input to the error amplifier. An external resistive divider from VOUT to GND is compared to the internal 0.794V (typ) reference to set the regulation voltage.
4	EN	input	Enable input. Pull above the enable threshold (Venh 1.6V min, 2.0V max) to enable; pull below to disable. Internally pulled to ground when floating; internally clamped to ~7.5V. Connect a 100kΩ resistor to VIN to auto-enable.
5	VIN	power_in	Input supply, 4.2V to 40V operating (absolute max 43V). Powers all internal control circuits and the high-side switching MOSFET. Requires a decoupling capacitor to GND placed close to this pin to reduce switching spikes.
6	SW	output	Switch node - output of the internal high-side MOSFET drain. Connect the inductor here and a low-VF Schottky catch diode to GND close to this pin. Absolute max VSW = VIN(MAX)+0.3V.

Key specifications

Parameter	Value
Manufacturer	Shanghai Siproin Microelectronics
Package	SOT-23-6
Category	PMIC
Pins	6

Ordering variants

Same part, different packaging or reel option.

SSP9451

CAD (KiCad official)

Symbol: SSP9451
Footprint: Package_TO_SOT_SMD:SOT-23-6
3D model: SOT-23-6 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`ssp9451.step`	97 KB	You want the bare part, or you mark your own boards.
`ssp9451-etched.step`	1.7 MB	You want the part with `SSP9451` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 409 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: Shanghai Siproin Microelectronics datasheet (13 pp, sha256 7829d7b5652b6515, 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