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

Overview

We are offering these compact breakout boards with support from Allegro Microsystems as an easy way to use or evaluate their ACS72981xLR Hall effect-based linear current sensors; we therefore recommend careful reading of the ACS72981 datasheet before using this product. The following list details some of the sensor’s key features:

• Differential Hall sensing rejects common-mode fields, so the orientation of the sensor relative to uniform external magnetic fields (e.g. the Earth’s magnetic field) has less effect on the measurement.
• The conductive path internal resistance is typically 0.2 mΩ, and the PCB is made with 6 layers of 2-oz copper, so very little power is lost in the module.
• Use of a Hall effect sensor means the IC is able to electrically isolate the current path from the sensor’s electronics, which allows the sensor to be inserted anywhere along the current path and to be used in applications that require electrical isolation.
• High-bandwidth 250 kHz analog output voltage proportional to AC or DC currents.
• Less than 2 µs response time.
• 3.3V and 5V versions available.
• Integrated digital temperature compensation circuitry allows improved accuracy over the full operating temperature range.
• Carrier board offers a variety of ways to insert it into the current path and 0.1″-pitch (breadboard compatible) power, ground, and output pins.

The pads are labeled on the bottom silkscreen. The silkscreen also shows the direction that is interpreted as positive current flow via the +i arrow.

The following table lists the available ACS72981 carrier options:

Pololu Item #	Part Suffix	Supply Voltage	Current Range		Sensitivity @ Nominal Vcc	Zero Point @ Nominal Vcc	Size
#5250	050B3	3.0 V to 3.6 V (3.3 V nominal)	Bidirectional	±50 A	26.4 mV/A	1.65 V	0.7″×0.8″ (compact carrier)
#5253	100B3			±100 A	13.2 mV/A
#5257	150B3			±150 A	8.8 mV/A
#5252	050U3		Unidirectional	0-50 A	52.8 mV/A	0.33 V
#5255	100U3			0-100 A	26.4 mV/A
#5259	150U3			0-150 A	17.6 mV/A
#5251	050B5	4.5 V to 5.5 V (5 V nominal)	Bidirectional	±50 A	40 mV/A	2.5 V
#5256	100U5		Unidirectional	0-100 A	40 mV/A	0.5 V

Details for item #5252

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

ACS72981 Current Sensor Compact Carrier.

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.

Part Suffix	Range	Supply Voltage	Sensitivity @ 3.3 V	Zero Point @ 3.3 V	Size
050U3	0-50 A (unidirectional)	3.0 V to 3.6 V	52.8 mV/A	0.33 V	0.7″×0.8″

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:

``text(VIOUT) = text(VCC) / 10 + 0.0528 V/A * text(VCC) / (3.3 V) * text(IP) = text(VCC) * (1/10 + text(IP) / (62.5 A))``

``text(IP) = 62.5A * (text(VIOUT) / text(VCC) – 1/10)``

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 (264k pdf).

Comparison of the Pololu current sensor carriers

We have a variety of current sensors available with different ranges, sensitivities, and features. The table below summarizes our selection of active and preferred options: