MCP16331T-E from Microchip, 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	BOOST	passive	Boost pin. Supply for the floating high-side driver used to switch the integrated N-channel MOSFET. An external bootstrap capacitor (typ. 100 nF) is connected between BOOST and SW, and a small blocking diode (e.g. 1N4148) charges it from VOUT. VBOOST - VSW must remain within 3.0V to 5.5V for proper high-side drive.
2	GND	power_in	Device ground / return pin. Input-cap return, output-cap return and GND trace should be as short as possible to minimize noise on this node.
3	VFB	input	Output voltage feedback pin. Connect to the midpoint of an external resistor divider from VOUT to GND to program the output voltage. The internal reference is 0.800V typical (0.784V to 0.816V); feedback input bias current is ±3 nA typical.
4	EN	input	Enable pin. Logic-level input with an internal pull-up to VIN, so the device starts even if EN is left floating. Drive low (VIL ≤ 0.4V) or tie to GND to shut the regulator off (shutdown IQ ≈ 6 µA); drive high (VIH ≥ 1.9V) to enable. Absolute maximum is -0.5V to (VIN + 0.3V).
5	VIN	power_in	Power supply input pin for the power stage and internal biasing, 4.4V to 50V (54V abs max). Decouple to GND with a 4.7 µF to 20 µF ceramic capacitor placed as close as possible to VIN and GND. Undervoltage lockout starts operation at 4.1V typ (4.4V max) and stops at 3.6V typ (3.0V min).
6	SW	output	Switch node. Drain of the internal 600 mΩ N-channel high-side MOSFET; connects externally to the inductor, freewheeling Schottky diode (100V) and bootstrap capacitor. Absolute maximum VIN-SW is 54V; BOOST-SW is limited to 6.0V.

Key specifications

Parameter	Value
Manufacturer	Microchip
Package	SOT-23-6
Category	PMIC
Pins	6

Ordering variants

Same part, different packaging or reel option.

MCP16331T-E/CH
MCP16331T-E/MNY

CAD (KiCad official)

Symbol: MCP16331T-E
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
`mcp16331t-e.step`	97 KB	You want the bare part, or you mark your own boards.
`mcp16331t-e-etched.step`	1.9 MB	You want the part with `MCP16331T-E` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 484 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: Microchip datasheet (44 pp, sha256 bfd74d5f66667f16, 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