This is the compact version of a simple carrier for Allegro’s ACS72981LLRATR-100U3/U5 Hall effect-based, electrically isolated current sensor, which offers a low-resistance (~0.2 mΩ) current path and a high 250 kHz bandwidth for fast response times.

We are offering these breakout boards with support from Allegro Microsystems as an easy way to use or evaluate their ACS72981xLR Hall effect-based, electrically isolated 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:

• Hall effect-based sensor with electrically isolated current path allows the sensor to be inserted anywhere along the current path and to be used in applications that require electrical isolation.
• 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.
• High-bandwidth 250 kHz analog output voltage proportional to AC or DC currents
• Less than 2 µs response time.
• Integrated digital temperature compensation circuitry allows improved accuracy over the full operating temperature range.
• Carrier boards, available in compact and large sizes, offer a variety of ways to insert it into the current path and 0.1″-pitch (breadboard compatible) power, ground, and output pins.
• 3.3V and 5V versions available.
• Unidirectional and bidirectional versions available.
• The connection points are labeled on the bottom silkscreen. The silkscreen also shows the direction that is interpreted as positive current flow via the +i arrow.

Details for item #5255

This compact carrier features the ACS72981LLRATR-100U3, which is intended for nominal 3.3 V operation and is designed for unidirectional input current from 0 A to 100 A. This version can be visually distinguished from the other versions by the “3V3 U10” 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.

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 26.4 mV × (VCC/3.3 V) per amp of input current:

• VIOUT=VCC10+0.0264VA⋅VCC3.3V⋅IP=VCC⋅(110+IP125A)
• IP=125A⋅(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.

Details for item #5256

This compact carrier features the ACS72981LLRATR-100U5, which is intended for nominal 5 V operation and is designed for unidirectional input current from 0 A to 100 A. This version can be visually distinguished from the other versions by the “5V U10” 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 4.5 V to 5.5 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 40 mV × (VCC/5 V) per amp of input current:

• VIOUT=VCC10+0.04VA⋅VCC5V⋅IP=VCC⋅(110+IP125A)
• IP=125A⋅(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.

• Sensitivity when Vcc = 3.3 V; sensitivity is ratiometric.
• Sensitivity when Vcc = 5 V; sensitivity is ratiometric.
• Bandwidth can be reduced by adding a filter capacitor.
• ±50A version uses 4-oz copper PCB; all other versions use 2-oz copper.

Documentations:

• Schematic and dimension diagrams

Package Includes:

• 1 x Pololu 5255 / 5256 ACS72981LLRATR-100U3/U5 Current Sensor Compact Carrier 0A to 100A, 3.3V/5V