ACS72981LLRATR-050U3 Current Sensor Compact Carrier 0A to 50A, 3.3V

Large Carrier	#5270	050B3	3.0 to 3.6 (3.3 nominal)	Bidirectional	±50 A	26.4	1.65	1.4"×1.2"
	#5273	100B3			±100 A	13.2
	#5277	150B3			±150 A	8.8
	#5272	050U3		Unidirectional	0-50 A	52.8	0.33
	#5275	100U3			0-100 A	26.4
	#5279	150U3			0-150 A	17.6
	#5283	200U3			0-200 A	13.2
	#5271	050B5	4.5 to 5.5 (5 nominal)	Bidirectional	±50 A	40	2.5
	#5274	100B5			±100 A	20
	#5278	150B5			±150 A	13.3
	#5282	200B5			±200 A	10
	#5276	100U5		Unidirectional	0-100 A	40	0.5
	#5280	150U5			0-150 A	26.7
Compact Carrier	#5250	050B3	3.0 to 3.6 (3.3 nominal)	Bidirectional	±50 A	26.4	1.65	0.7"×0.8"
	#5253	100B3			±100 A	13.2
	#5257	150B3			±150 A	8.8
	#5252	050U3		Unidirectional	0-50 A	52.8	0.33
	#5255	100U3			0-100 A	26.4
	#5259	150U3			0-150 A	17.6
	#5263	200U3			0-200 A	13.2
	#5251	050B5	4.5 to 5.5 (5 nominal)	Bidirectional	±50 A	40	2.5
	#5254	100B5			±100 A	20
	#5258	150B5			±150 A	13.3
	#5262	200B5			±200 A	10
	#5256	100U5		Unidirectional	0-100 A	40	0.5
	#5260	150U5			0-150 A	26.7

ACS72981LLRATR-050U3 Current Sensor Compact Carrier 0A to 50A, 3.3V, bottom view.

This compact carrier features the ACS72981LLRATR-050U3, which is intended for nominal 3.3 V operation and is designed for unidirectional input current from 0 A to 50 A. This version can be visually distinguished from the other versions by the “3V3 U05” printed on the bottom side, as shown in the left picture above.

A larger carrier is also available for this sensor IC with room for larger connectors and thicker wires for the high-current path, offering different ways to use or evaluate this current sensor.

Using the sensor

This sensor has five required connections: the input current (IP+ and IP-), logic power (VCC and GND), and the sensor output (VIOUT).

The sensor requires a supply voltage of 3.0 V to 3.6 V to be connected across the VCC and GND pads, which are labeled on the bottom silkscreen. The sensor outputs a ratiometric analog voltage on VIOUT that has a zero point at VCC/10 and increases by 52.8 mV × (VCC/3.3 V) per amp of input current:

VIOUT=VCC10+0.0528VA⋅VCC3.3V⋅IP=VCC⋅(110+IP62.5A)" role="presentation" style="position: relative;">VIOUT=VCC10+0.0528VA·VCC3.3V·IP=VCC·(110+IP62.5A)VIOUT=VCC10+0.0528VA·VCC3.3V·IP=VCC·(110+IP62.5A)

IP=62.5A⋅(VIOUTVCC–110)" role="presentation" style="position: relative;">IP=62.5A·(VIOUTVCC–110)IP=62.5A·(VIOUTVCC–110)

The VIOUT, VCC, and GND pins work with 0.1"-pitch header pins and are compatible with standard solderless breadboards.

You can insert the board into your current path in a variety of ways. For typical high-current applications, you can solder wires directly to the through-holes that best match your wires, or you can use solderless ring terminal connectors, as shown in the pictures below. The largest through-holes are big enough for 8 AWG wires or #6 or M3.5 screws, and the second-largest through-holes (and mounting holes) are sized for 12 AWG wires or #2 or M2 screws. Holes with 0.1", 3.5 mm, and 5 mm spacing are also available as shown in the diagram above for connecting male header pins or terminal blocks, but please note that these connection options will generally not be suitable for the kinds of high currents intended for this sensor.

Warning: This product is intended for use below 30 V. Working with higher voltages can be extremely dangerous and should only be attempted by qualified individuals with appropriate equipment and experience.

Schematic and dimension diagrams

ACS72981 Current Sensor Carrier schematic diagram.

The dimension diagram is available as a downloadable PDF (400k pdf).

Real-world power dissipation considerations

Thermal image of a high-current test of a Pololu current sensor carrier (not necessarily this product).

Depending on the version, the ACS72981 can measure up to ±200 A, but its datasheet specifies an absolute maximum continuous current of 120 A. Furthermore, the sensor chip can overheat at lower currents. In Pololu's tests, Pololu found that Pololu's ACS72981 carrier boards could conduct 60 A continuously while staying well below the thermal limit for the IC. Pololu's tests were conducted at approximately 25°C ambient temperature with no forced air flow.

The actual current you can pass through the sensor will depend on how well you can keep it cool. The carrier’s printed circuit board is designed to help with this by drawing heat out of the sensor chip. Solid connections to the current path pins (such as with thick soldered wires or large, tightly-secured lugs) can also help reduce heat build-up in the sensor and carrier board.

Warning: Exceeding temperature or current limits can cause permanent damage to the sensor. If you are measuring an average continuous current greater than 50 A, Pololu strongly recommend that you monitor the sensor’s temperature and look into additional cooling if necessary.

This product can get hot enough to burn you long before the chip overheats. Take care when handling this product and other components connected to it.

Dimensions

General specifications

Notes:

Identifying markings

File downloads

• Dimension diagrams of the ACS72981xLR Current Sensor Carriers (400k pdf)

• 3D model of the ACS72981xLR Current Sensor Compact Carriers (3MB step)

• Drill guide for the ACS72981xLR Current Sensor Compact Carriers (18k dxf)

  This DXF drawing shows the locations of all of the board’s holes.

Recommended links

• ACS72981 datasheet

• Allegro Application Note AN296169: Characterizing System Bandwidth in Complex Current Sensor Applications

  This is the application note referenced on page 16 of the ACS724 datasheet, page 22 of the ACS71240 datasheet, and page 42 of the ACS72981xLR datasheet. The ACS720 is used validate the test methods presented, but these same methods and principles would also apply to the ACS724, ACS71240, and ACS72981.