Amplifies the small voltage across a shunt resistor into a ground-referenced output a plain ADC can read. The inputs sense a common-mode bus from -0.2 V to 26 V independent of the supply, so it works high-side or low-side, and a REF pin sets the zero-current output for bidirectional current. The fixed-gain part comes in 20, 50, 100, and 200 V/V options (A1-A4). Runs from a single 2.7 to 5.5 V rail. The single-channel workhorse for board-level current measurement.

Pinout

Pin	Name	Type	Function
1	OUT	output	Analog output voltage. V_OUT = Gain x (V_IN+ - V_IN-) + V_REF. Rail-to-rail output.
2	GND	power_in	Device ground reference.
3	IN+	input	Current-sense amplifier positive input. For high-side sensing, connect to the bus-voltage side of the sense resistor; for low-side sensing, connect to the load side. Common-mode range -0.2 V to +26 V.
4	IN-	input	Current-sense amplifier negative input. For high-side sensing, connect to the load side of the sense resistor; for low-side sensing, connect to the ground side. Common-mode range -0.2 V to +26 V.
5	REF	input	Reference input that sets the output voltage for zero differential input. Tie to GND for unidirectional sensing or to a mid-supply reference for bidirectional sensing. Valid range 0 V to VS.
6	VS	power_in	Positive supply. Operating range 2.7 V to 5.5 V. Quiescent current 260 uA (max, INA181). Bypass with 0.1 uF ceramic to GND close to the pin.

Key specifications

Parameter	Value
Type	Current-sense amplifier (voltage output)
Common-mode range	-0.2 V to 26 V
Gain options	20 / 50 / 100 / 200 V/V (A1-A4)
Bandwidth	350 kHz (gain 20)
Direction	Bidirectional (via REF)
Supply	2.7-5.5 V
Package	SOT-23-6

Ordering variants

Same part, different packaging or reel option.

INA181A1IDBVR (gain 20)
INA181A2IDBVR (gain 50)
INA181A3IDBVR (gain 100)
INA181A4IDBVR (gain 200)

CAD (KiCad official)

Symbol: Amplifier_Current:INA181 (KiCad official)
Footprint: Package_TO_SOT_SMD:SOT-23-6
3D model: SOT-23-6 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Texas Instruments datasheet (62 pp, sha256 b8e948e4b605ffaa, 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