FM4057E42 from Shenzhen Fuman, in a ESOP-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	NC	unconnected	No internal connection. Leave floating or tie to GND.
2	ISET	input	Charge-current programming input. An external resistor from ISET to GND sets the constant-current charge level (typ. 1.0A at 3kΩ, 0.6A at 5kΩ, 0.5A at 6kΩ). Also sets precharge (~60mA at 5kΩ) and termination (~60mA at 5kΩ) thresholds.
3	GND	power_in	Device ground / analog reference for VIN, BAT, ISET, and the LED status outputs.
4	VIN	power_in	Charger input supply. Recommended operating range 4.2V-6.5V (typ. 5V); withstands up to 32V. Internal VIN OVP trips at 6.5V (0.5V hysteresis) and UVLO at 4.6V rising / 4.2V falling. Bypass with ≥4.7µF (a 1µF may be used per app circuit).
5	BAT	power_out	Battery connection to the single-cell Li-ion pack. E42 regulates to 4.2V (V_BAT_FULL = 4.158/4.2/4.242V). Recharge threshold ~4.05V, battery OVP at 104%·V_BAT. Requires ~10µF bypass capacitor to GND.
6	DONE	output	Open-drain charge-complete status indicator. Sinks current through an external LED (to VIN via limit resistor): LED is off during charging and turns on solid when charging is complete.
7	CHRG	output	Open-drain charging status indicator. Sinks current through an external LED (to VIN via limit resistor): LED is on while charging and turns off when charging completes.
8	NC	unconnected	No internal connection. Leave floating or tie to GND.
9	EPAD	power_in	Exposed thermal pad on package underside. Must be soldered to the PCB ground plane for the specified thermal performance; electrically connected to GND (散热地).

Key specifications

Parameter	Value
Manufacturer	Shenzhen Fuman
Package	ESOP-8
Category	PMIC
Pins	9

Ordering variants

Same part, different packaging or reel option.

FM4057E42
FM4057E42E43
FM4057E42E44
FM4057E42BE42
FM4057E42S42
FM4057E42S43
FM4057E42S44
FM4057E42S52
FM4057E42BS52
FM4057E42S53
FM4057E42S54
FM4057E42D42
FM4057E42D43
FM4057E42D44

CAD (KiCad official)

Symbol: FM4057E42
Footprint: Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.41x3.3mm
3D model: ESOP-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`fm4057e42.step`	193 KB	You want the bare part, or you mark your own boards.
`fm4057e42-etched.step`	1.4 MB	You want the part with `FM4057E42` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 370 faces against 63 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: Shenzhen Fuman datasheet (14 pp, sha256 bfc23830eabbc3b5, retrieved 2026-08-17, tier: lcsc)
Datasheet language: Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
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