This board is a simple carrier of Allegro’s ACS71240KEXBLT-050B3/030B3/010B3 Hall effect-based, electrically isolated current sensor, which offers a low-resistance (~0.6 mΩ) current path and a high 120 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 ACS71240 Hall effect-based, electrically isolated current sensors with overcurrent fault output; we therefore recommend careful reading of the ACS71240 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 0.6 mΩ, and the PCB is made with 2-oz copper, so very little power is lost in the module.
• High-bandwidth 120 kHz analog output voltage proportional to AC or DC currents.
• Less than 5 µs response time.
• Output is not ratiometric (i.e. the zero point and sensitivity are independent of the actual supply voltage), which provides immunity from noisy supplies.
• Overcurrent fault output with 1.5 µs response time indicates when the current exceeds the optimized sensing range and can be used for fast short-circuit detection.
• 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.
• 3.3V and 5V versions available.
• Unidirectional and bidirectional versions available.

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.

Details for item #5242 (-50A to +50A, 3.3V)

This carrier features the ACS71240KEXBLT-050B3, which is intended for operation around 3.3 V and is designed for bidirectional input current from -50 A to +50 A. This version can be visually distinguished from the other versions by the “3V3 B50” 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 labeled on the bottom silkscreen. The sensor outputs an analog voltage on VIOUT that is centered at 1.65 V and changes by 26.4 mV per amp of input current, with positive current increasing the output voltage and negative current decreasing the output voltage:

• VIOUT=1.65V+0.0264VA⋅IP
• IP=VIOUT–1.65V0.0264VA=(VIOUT–1.65V)⋅37.9AV

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 50 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.

Details for item #5241 (-30A to +30A, 3.3V)

• 1 x Pololu 5242 / 5241 / 5240 ACS71240KEXBLT-050B3/030B3/010B3 Current Sensor Carrier 3.3V