PJ4054B from PJSEMI, in a SOT-23-5. 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 output. Pulled low by an internal N-channel MOSFET while battery charging is in progress (VCHRG(low) <= 0.6V at ICHRG = 5mA). Goes high-impedance when the charge cycle terminates or when VCC is in undervoltage lockout. Typically drives an indicator LED to VIN through a series resistor (e.g. 1k).
2	GND	power_in	Device ground reference.
3	BAT	power_out	Charging current output to the lithium-ion battery. Regulates the final float voltage to 4.2V (typ, 4.158-4.242V) via a precise internal resistor divider that is disconnected in shutdown. Sourcing capability up to 500mA (typical) set by RPROG. Bypass with ~10uF ceramic capacitor to ground.
4	VCC	power_in	Positive input supply to the charger. Operating range 4.25V to 6.5V (absolute max VSS+7V); bypass with at least 1uF (typically 4.7uF) to GND. When VCC falls to within ~30mV of VBAT, or below the UVLO threshold (~3.8V), the part enters standby/stop mode and IBAT drops below ~2uA.
5	PROG	bidirectional	Charge current programming, monitor, and manual-shutdown pin. Connect a 1% resistor RPROG from PROG to GND: IBAT = (VPROG/RPROG) * 1000 (e.g. 2kOhm -> 500mA, 10kOhm -> 100mA). Pin regulates to 1V (typ) in constant-current mode and can be measured as a current-monitor output. Leaving the resistor floating pulls the pin above the 1.21V (typ) shutdown threshold via an internal ~2.5uA (2uA typ) pull-up, forcing the charger into stop mode (ICC ~= 25uA).

Key specifications

Parameter	Value
Manufacturer	PJSEMI
Package	SOT-23-5
Category	PMIC
Pins	5

CAD (KiCad official)

Symbol: PJ4054B
Footprint: Package_TO_SOT_SMD:SOT-23-5
3D model: SOT-23-5 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`pj4054b.step`	85 KB	You want the bare part, or you mark your own boards.
`pj4054b-etched.step`	1.5 MB	You want the part with `PJ4054B` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 366 faces against 102 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: PJSEMI datasheet (6 pp, sha256 71f5fc869da0b682, 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