WS4054 from WPMtek Wei Pan Microelectronics, in a SOT-23-5L. 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	CHRG	output	Open-drain charge status indicator. Pulled low (LED on) during an active charge cycle; high-Z (LED off) when charging terminates, VDD is in UVLO, or VBAT > VDD. Blinks when VDD is valid, BAT is connected only to a ~2.2 uF capacitor and no battery is present. VCHRGL ≤ 100 mV at ICHRG = 5 mA. Tie to ground through a series LED + ~1 kΩ resistor from VIN, or leave unconnected if unused.
2	GND	power_in	Device ground reference. Connect to system ground with a low-impedance path; PROG resistor and input/output bypass capacitors return here.
3	BAT	power_out	Charge current output to the single-cell Li-ion battery. Regulates to VFLOAT = 4.200 V ±42 mV in constant-voltage mode. Sources programmed constant current (up to 500 mA) in CC mode and ~1/10 of the programmed current as trickle when VBAT < VTRKL (2.9 V). Recharge cycle restarts when VBAT falls ~150 mV below VFLOAT (≈ 4.05 V). Bypass with ~1-10 uF ceramic capacitor to GND.
4	VDD	power_in	Input supply from USB port or AC adapter. Recommended operating range 4.5 V-6.0 V (absolute max 9 V, but reverse-connected-battery operation should stay near 5 V and not exceed 6 V). UVLO threshold typ 3.7 V rising with 170 mV hysteresis; charger stays disabled until VDD > VBAT + 200 mV. Bypass with 1-10 uF ceramic capacitor to GND close to the pin.
5	PROG	passive	Charge-current program pin. Connect a resistor RPROG from PROG to GND to set the fast-charge current: IBAT ≈ 1000 / RPROG (A·Ω), e.g. 2 kΩ → 500 mA, 4 kΩ → 250 mA, 10 kΩ → 100 mA, 20 kΩ → 50 mA. Servos to VPROG2 ≈ 1.00 V in constant-current mode. Floating or open PROG puts the part into standby; termination is detected when the PROG voltage falls below 100 mV for TDELAY.

Key specifications

Parameter	Value
Manufacturer	WPMtek Wei Pan Microelectronics
Package	SOT-23-5L
Category	PMIC
Pins	5

Ordering variants

Same part, different packaging or reel option.

WS4054

CAD (KiCad official)

Symbol: WS4054
Footprint: Package_TO_SOT_SMD:SOT-23-5
3D model: SOT-23-5L (KiCad packages3D, STEP)

Provenance

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

Datasheet: WPMtek Wei Pan Microelectronics datasheet (8 pp, sha256 92880727123ac84b, 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