FR9855SP from Fitipower Integrated 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	SHDN	input	Active-low shutdown / enable and mode-select input. SHDN=0V shuts the device down; 1.5V-2.5V selects forced PWM mode; >3.5V selects power-saving (PSM) mode. Tie to VIN through a 100kΩ resistor for self-startup in power-saving mode. Absolute max 20V; VIH(min)=1.5V, VIL(max)=0.5V.
2	FB	input	Voltage feedback input. Connect to VOUT via a resistive divider; the loop regulates FB to VFB = 0.765V (typ, 0.75V-0.78V). Feedback input current is 0.01µA typ.
3	PG	output	Open-drain power-good output. Pulls low when VFB is below ~85% of Vref (falling) and releases above ~90% (rising). Sink capability ~4mA. Requires an external pull-up resistor.
4	SS	passive	Soft-start pin. Connect a capacitor from SS to GND to program the soft-start ramp period; the pin sources ~6µA (ISS) into the capacitor.
5	GND	power_in	Signal / power ground return.
6	LX	output	Switching node between the internal high-side (70mΩ) and low-side (38mΩ) power MOSFETs. Connect the external inductor here. Absolute max -0.3V to VIN+0.3V (transient -5V to VIN+5V for 15ns).
7	BST	passive	High-side gate-drive bootstrap pin. Connect a 0.1µF-1µF capacitor from BST to LX to fully enhance the internal high-side NMOS. Absolute max VBST = VLX + 6.5V.
8	VIN	power_in	Power supply input, 4.5V to 18V operating (absolute max 20V). Place input decoupling capacitors as close as possible to VIN and GND to minimize noise coupling.
9	EP	power_in	Exposed thermal pad on the package underside. Must be soldered to a large PCB copper area tied to GND for maximum power dissipation (θJA = 60°C/W, θJC = 15°C/W).

Key specifications

Parameter	Value
Manufacturer	Fitipower Integrated Tech
Package	SOIC-8-EP
Category	PMIC
Pins	9

Ordering variants

Same part, different packaging or reel option.

FR9855SP
FR9855SPDA

CAD (KiCad official)

Symbol: FR9855SP
Footprint: Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.29x3mm
3D model: SOIC-8-EP (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Fitipower Integrated Tech datasheet (16 pp, sha256 b6dded9e25acc343, 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