RT9045GSP from Richtek Tech, in a SOIC-8. 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	VIN	power_in	Input voltage supplying current to the output pin (1V to 5.5V recommended, absolute max 6V). Must be kept lower or equal to VCNTL. Decouple with a large low-ESR ceramic capacitor (typ. 10µF) placed close to the pin.
2	GND	power_in	Common ground. Shared with the exposed pad, which must be soldered to a large PCB copper area connected to GND for maximum power dissipation.
3	REFEN	input	Reference voltage input and active-low shutdown control pin. Two resistors divide VIN on this pin to program the regulated output voltage (V_OUT = V_REFEN). Pulling this pin to ground (V_REFEN < 0.15V) shuts down the device; typical drive uses an open-drain N-MOSFET such as 2N7002.
4	VOUT	power_out	Regulator output, regulated to the REFEN voltage to terminate the DDR bus resistors. Capable of sinking and sourcing up to 1.8A. Requires typ. 10µF ceramic output capacitance to maintain large-signal transient response.
5	NC	unconnected	No internal connection. Leave floating or tie to GND.
6	VCNTL	power_in	Control/bias supply for internal control circuitry and gate drive to the output power MOSFETs (5V ±5%). Output current drive capability is proportional to VCNTL. Decouple with at least 1µF to GND; VIN must be kept ≤ VCNTL.
7	NC	unconnected	No internal connection. Leave floating or tie to GND.
8	NC	unconnected	No internal connection. Leave floating or tie to GND.
9	GND (Exposed Pad)	power_in	Exposed thermal pad on the package underside. Must be soldered to a large PCB copper area connected to GND for proper heat sinking and rated power dissipation (2.51W at TA=25°C, θJA=39.8°C/W).

Key specifications

Parameter	Value
Manufacturer	Richtek Tech
Package	SOIC-8
Category	PMIC
Pins	9

Ordering variants

Same part, different packaging or reel option.

RT9045GSP
RT9045GSPZSP

CAD (KiCad official)

Symbol: RT9045GSP
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOIC-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`rt9045gsp.step`	122 KB	You want the bare part, or you mark your own boards.
`rt9045gsp-etched.step`	2.2 MB	You want the part with `RT9045GSP` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 530 faces against 147 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: Richtek Tech datasheet (11 pp, sha256 ecb44d14a5f14751, 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