ACS71240KEXBLT-030B3 Current Sensor Carrier -30A to +30A, 3.3V

Overview

We are offering these breakout boards with support from Allegro Microsystems as an easy way to use or evaluate their ACS71240 Hall effect-based linear current sensors; we therefore recommend careful reading of the ACS71240 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 0.6 mΩ, and the PCB is made with 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 120 kHz analogue output voltage proportional to AC or DC currents.
• Overcurrent fault output with 1.5 µs response time indicates when the current exceeds the optimised sensing range.
• Output is not ratiometric (i.e. the zero point and sensitivity are independent of the actual supply voltage), which provides immunity from noisy supplies.
• Integrated digital temperature compensation circuitry allows for near closed loop accuracy over temperature in an open loop sensor.
• Automotive-grade operating temperature range of -40°C to 125°C.
• 0.7″×0.8″ 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 labelled on the bottom silkscreen. The silkscreen also shows the direction that is interpreted as positive current flow via the +i arrow.

Details for item #5241

This carrier features the ACS71240KEXBLT-030B3, which is intended for operation around 3.3 V and is designed for bidirectional input current from -30 A to +30 A. This version can be visually distinguished from the other versions by the “3V3 B30” printed on the bottom side, as shown in the left picture above.

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 labelled on the bottom silkscreen. The sensor outputs an analogue voltage on VIOUT that is centred at 1.65 V and changes by 44 mV per amp of input current, with positive current increasing the output voltage and negative current decreasing the output voltage:

``text(VIOUT) = 1.65 V + 0.044 V/A * text(IP)``

``text(IP) = (text(VIOUT) – 1.65 V) / (0.044 V/A) = (text(VIOUT) – 1.65 V) * 22.7 A/V ``

The output is not ratiometric, so the zero point and sensitivity are independent of the actual supply voltage.

The optional FAULT pin is normally at VCC and is pulled low when the IP current magnitude exceeds 30 A in either direction. This pin only asserts while the fault condition is present (it is not latched).

The FAULT, 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. Holes with 0.1″, 3.5 mm, and 5 mm spacing are available as shown in the diagram above for connecting male header pins or terminal blocks. For 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. 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. The pictures below show some of the possible connection options:

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

The dimension diagram is available as a downloadable PDF (274k 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:

Dimensions

General specifications

Identifying markings

Notes:

1

Max.

File downloads

• Dimension diagram of the ACS71240 Current Sensor Carrier (274k pdf)

• 3D model of the ACS711EX and ACS71240 Current Sensor Carrier (3MB step)

• Drill guide for ACS711EX and ACS71240 Current Sensor Carrier (18k dxf)

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

Recommended links

• ACS71240 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.

• Allegro product page for the ACS71240 Hall-based Current Sensor

  Allegro product page for the ACS71240, where you can find additional application notes and other resources.