BD9G401EFJ-ME2 from ROHM, in a HTSOP-8-EP. 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	LX	output	Switching node. Drain of the internal high-side N-channel power MOSFET (RonH = 140 mΩ typ); connect the external inductor and catch diode here. Absolute max LX-GND = 45 V.
2	GND	power_in	Device ground return for the power stage and control logic. Also serves as the reference for all pin voltage limits.
3	VC	output	Error amplifier output / compensation node. Connect an external RC network to GND to set the loop compensation. Absolute max VC-GND = 7 V.
4	FB	input	Feedback input to the error amplifier. Internal reference is 0.8 V (typ); connect a resistor divider from VOUT to set the output voltage. Absolute max FB-GND = 7 V.
5	SYNC	input	External clock synchronization input, 250 kHz to 500 kHz. VIH ≥ 2.0 V, VIL ≤ 0.8 V; internally pulled down. Tie to GND when the synchronization function is not used. Absolute max SYNC-GND = 7 V.
6	EN	input	Enable / on-off input. VEN < 0.3 V = IC off; 0.3-1.4 V turns internal REG on; > 1.8 V (typ) enables the IC with 10 µA (typ) source current hysteresis. May be driven from a resistor divider off VCC for arbitrary UVLO. Absolute max EN-GND = 45 V.
7	BST	passive	Bootstrap capacitor terminal for the high-side FET gate drive. Connect a 0.1 µF capacitor from BST to LX. Absolute max BST-GND = 50 V, BST-LX = 7 V.
8	VCC	power_in	Input supply pin, 4.5 V to 42 V operating (4.65 V required for start-up). Bypass with a 10 µF / 50 V ceramic close to the pin. Absolute max VCC-GND = 45 V.
9	THERMAL_PAD	passive	Exposed thermal pad on the package underside. Must always be connected to GND and to a copper heat-spreading area/thermal vias for heat dissipation.

Key specifications

Parameter	Value
Manufacturer	ROHM
Package	HTSOP-8-EP
Category	PMIC
Pins	9

Ordering variants

BD9G401EFJ-ME2

CAD (KiCad official)

Symbol: BD9G401EFJ-ME2
Footprint: Package_SO:HTSOP-8-1EP_3.9x4.9mm_P1.27mm_EP2.4x3.2mm
3D model: HTSOP-8-EP (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`bd9g401efj-me2.step`	127 KB	You want the bare part, or you mark your own boards.
`bd9g401efj-me2-etched.step`	2.5 MB	You want the part with `BD9G401EFJ-ME2` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 629 faces against 152 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: ROHM datasheet (31 pp, sha256 2dfe5ab3693fd35c, 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