RT7257BHZSP from Richtek Tech, in a SOIC-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	BOOT	power_in	Bootstrap for high-side gate driver. Connect a 0.1μF or greater ceramic capacitor from BOOT to SW. V(BOOT)-V(SW) absolute max 6V.
2	VIN	power_in	Input supply voltage, 4.5V to 18V (abs max 20V). Must be bypassed with a suitable large ceramic capacitor (e.g. 10μF x2 + 0.1μF).
3	SW	power_out	Switch node. Connect to an external L-C output filter. Swings between GND and VIN at up to 1.2MHz. High-side RDS(on) 110mΩ, low-side 90mΩ.
4,9	GND	power_in	Ground. Pin 4 and the exposed pad (pin 9) must both be soldered to a large PCB copper area connected to GND for maximum power dissipation (θJA 75°C/W with exposed pad).
5	FB	input	Feedback input. Regulates the output via an external resistive voltage divider. Internal reference VREF = 0.8V (±1.5%).
6	COMP	output	Compensation node for the regulation control loop. Connect a series R-C network from COMP to GND; an optional additional capacitor from COMP to GND may be required in some cases.
7	EN	input	Enable input. Logic high (VIH ≥ 2.7V) enables the converter; logic low (VIL ≤ 0.4V) puts the device into shutdown (<3μA supply). Tie to VIN via a 100kΩ pull-up for automatic startup. Absolute max 20V.
8	SS	input	Soft-start control input. Connect a capacitor from SS to GND to set the soft-start period; a 0.1μF cap gives ~13.5ms (ISS = 6μA typ).

Key specifications

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

Ordering variants

Same part, different packaging or reel option.

RT7257BHZSP
RT7257BHZSPLZSP

CAD (KiCad official)

Symbol: RT7257BHZSP
Footprint: Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.29x3mm
3D model: SOIC-8-EP (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`rt7257bhzsp.step`	125 KB	You want the bare part, or you mark your own boards.
`rt7257bhzsp-etched.step`	2.1 MB	You want the part with `RT7257BHZSP` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 531 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: Richtek Tech datasheet (14 pp, sha256 f9aaf4883cb3a8fc, 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