Miniature, fully integrated single-cell Li-Ion / Li-Polymer linear charge-management controller in a SOT-23-5 package. It regulates a 4.20 V constant-voltage float with a constant-current phase set by one resistor on PROG (up to 500 mA), and integrates the pass transistor, current sensing, and reverse-discharge protection. A STAT pin drives a charge-status LED. The default USB-powered LiPo charger for small devices; just add the PROG resistor and a status LED.

Pinout

Pin	Name	Type	Function
1	STAT	tri_state	Charge Status Output. Tri-state logic output on the MCP73831 (open-drain on MCP73832). Drives an indicator LED directly (ISINK up to 25 mA, VOL ≈ 0.4 V at 4 mA; ISOURCE up to 35 mA, VOH ≥ VDD-1 at 4 mA) or can be pulled up for interfacing to a host microcontroller.
2	VSS	power_in	Battery Management 0 V Reference. Connect to the negative terminal of the battery and the input supply return.
3	VBAT	power_out	Battery Charge Control Output. Connect to the positive terminal of the single-cell Li-Ion/Li-Polymer battery; this is the drain of the internal P-channel MOSFET pass transistor (RDSON ≈ 350 mΩ). Bypass to VSS with a minimum of 4.7 µF to ensure loop stability when the battery is disconnected. Regulated to VREG (4.20/4.35/4.40/4.50 V option) at ±0.75%.
4	VDD	power_in	Battery Management Input Supply. Recommended range [VREG(typical) + 0.3 V] to 6 V (absolute max 7 V). Bypass to VSS with a minimum of 4.7 µF. Supply current is 510 µA typical while charging.
5	PROG	input	Current Regulation Set and Charge Control Enable. A resistor from PROG to VSS programs the preconditioning, fast-charge, and termination currents (RPROG range 2 kΩ to 67 kΩ; e.g., 2 kΩ → 505 mA, 10 kΩ → 100 mA, 67 kΩ → 14.5 mA typical). Allowing PROG to float (impedance ≥ 70 kΩ, minimum shutdown impedance) disables the charge management controller.

Key specifications

Parameter	Value
Type	Single-cell Li-Ion/LiPo linear charger
Regulation voltage	4.20 V (-2 variant)
Charge current	Programmable via PROG (15-500 mA)
Integrated	Pass transistor, current sense, reverse-discharge protection
Status	STAT open-drain (charge LED)
Preconditioning + termination	Automatic
Package	SOT-23-5
Body (L×W×H)	2.9 × 1.6 × 1.1 mm

Ordering variants

Same part, different packaging or reel option.

MCP73831T-2ACI/OT (SOT-23-5, 4.20 V)
MCP73831-2ACI/OT (SOT-23-5)

CAD (KiCad official)

Symbol: Battery_Management:MCP73831-2-OT
Footprint: Package_TO_SOT_SMD:SOT-23-5
3D model: SOT-23-5 (KiCad packages3D)

Provenance

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

Datasheet: Microchip Technology datasheet (29 pp, sha256 75297f2a52355993, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude) — every pin and dimension is cited to a datasheet page; refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF