BQ21040DBVR from Texas Instruments, in a SOT-23-6. 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	TS	input	Temperature sense terminal connected to a 10-kΩ (at 25°C) NTC thermistor in the battery pack. Floating or pulling this pin High places the part in TTDM (Charger) mode, disabling TS monitoring, timers, and termination. Pulling it Low disables the IC. If NTC sensing is not used, connect this pin to VSS through an external 10-kΩ resistor; a 237-kΩ resistor to TS will prevent entering TTDM when the battery has no thermistor.
2	OUT	power_out	Battery connection; the system load may also be connected here. Expected range of bypass capacitors is 1 µF to 10 µF. Sources charge current up to 800 mA and regulates to VOUT(REG) = 4.2 V.
3	/CHG	output	Open-drain charge-status indicator. Low (FET on) indicates charging in progress; Open (FET off) indicates no charging or charge complete. Max sink current 15 mA; typically drives a status LED to VIN.
4	ISET	input	Fast-charge current programming input. External resistor from ISET to VSS defines the fast-charge current (IOUT = KISET/RISET, KISET ≈ 540 A·Ω). Programmable resistor range 0.675 kΩ to 10.8 kΩ gives 50 mA to 800 mA.
5	GND	power_in	Ground / VSS reference terminal for the device.
6	VIN	power_in	Input power connection to external DC supply (AC adapter or USB port). Operating range 4.45 V to 6.45 V (recommended), absolute max 30 V with 6.6-V input overvoltage protection. Expected range of bypass capacitors 1 µF to 10 µF, connected from IN to VSS.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	SOT-23-6
Category	PMIC
Pins	6

Ordering variants

BQ21040DBVR
BQ21040DBVRDBVT

CAD (KiCad official)

Symbol: BQ21040DBVR
Footprint: Package_TO_SOT_SMD:SOT-23-6
3D model: SOT-23-6 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`bq21040dbvr.step`	97 KB	You want the bare part, or you mark your own boards.
`bq21040dbvr-etched.step`	2.2 MB	You want the part with `BQ21040DBVR` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 548 faces against 117 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: Texas Instruments datasheet (31 pp, sha256 66c454e4978439d2, retrieved 2026-08-17, tier: manufacturer)
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