This board is a simple carrier of Allegro’s ACS71240KEXBLT-050B3 Hall effect-based linear current sensor, which offers a low-resistance (~0.6 mΩ) current path and a high 120 kHz bandwidth for fast response times.
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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:
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.
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.
Part Suffix | Range | Supply Voltage | Sensitivity | Zero Point | Fault Trip Level |
---|---|---|---|---|---|
050B3 | ±50 A (bidirectional) | 3.0 V to 3.6 V | 26.4 mV/A | 1.65 V | ±50 A |
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 26.4 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 + 0.0264 V/A * text(IP)``
``text(IP) = (text(VIOUT) – 1.65 V) / (0.0264 V/A) = (text(VIOUT) – 1.65 V) * 37.9 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 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.
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.
The dimension diagram is available as a downloadable PDF (274k pdf).
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:
ACS711 CurrentSensor Carriers |
ACS71240 CurrentSensor Carriers |
ACS724 CurrentSensor Carriers |
ACS72981 CurrentSensor Carriers |
|
---|---|---|---|---|
Sensor IC: | Allegro ACS711KEXT |
Allegro ACS71240 |
Allegro ACS724LLCTR |
Allegro ACS72981xLR |
Vcc range: | 3 V–5.5 V | 3.3V versions: 3.0 V–3.6 V 5V versions: 4.5 V–5.5 V |
4.5 V–5.5 V | 3.3V versions: 3.0 V–3.6 V 5V versions: 4.5 V–5.5 V |
Current range / sensitivity: |
Bidirectional:(1) ±15.5 A / 90 mV/A ±31 A / 45 mV/A |
3.3V Bidirectional: ±10 A / 132 mV/A ±30 A / 44 mV/A ±50 A / 26.4 mV/A 5V Unidirectional: 0–50 A / 80 mv/A |
5V Bidirectional:(2) ±2.5 A / 800 mV/A ±5 A / 400 mV/A ±10 A / 200 mV/A ±20 A / 100 mV/A ±30 A / 66 mV/A ±50 A / 40 mV/A 5V Unidirectional:(2) 0–5 A / 800 mv/A 0–10 A / 400 mv/A 0–20 A / 200 mv/A 0–30 A / 133 mV/A |
3.3V Bidirectional:(1) ±50 A / 26.4 mV/A ±150 A / 8.8 mV/A 3.3V Unidirectional:(1) 0–50 A / 52.8 mv/A 0–100 A / 26.4 mv/A 5V Bidirectional:(2) ±50 A / 40 mV/A 5V Unidirectional:(2) 0–100 A / 40 mv/A |
IC path resistance: | 0.6 mΩ | 0.6 mΩ | 0.6 mΩ | 0.2 mΩ |
Max bandwidth: | 100 kHz | 120 kHz | 120 kHz(3) | 250 kHz |
Size: | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ |
Overcurrent fault output | ||||
Differential sensing | ||||
Non-ratiometric output | ||||
1-piece price: | $3.49 | $3.95 | $6.95 – $7.49 | $9.95 |
(1) Sensitivity when Vcc = 3.3 V; sensitivity is ratiometric. | ||||
(2) Sensitivity when Vcc = 5 V; sensitivity is ratiometric. | ||||
(3) Bandwidth can be reduced by adding a filter capacitor. |
Size: | 0.7" x 0.8" |
---|---|
Weight: | 1.1 g |
Typical operating voltage: | 3.3 V |
---|---|
Current sense: | 26.4 mV/A |
Minimum logic voltage: | 3.0 V |
Maximum logic voltage: | 3.6 V |
Supply current: | 12 mA1 |
Version: | -50A to +50A (bidirectional 50A), 3.3V |
Current sensor: | Allegro ACS71240KEXBLT-050B3 |
PCB dev codes: | cs02b |
---|---|
Other PCB markings: | 0J7387 |
Other PCB markings: | 3V3 B50 |
This DXF drawing shows the locations of all of the board’s holes.
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, where you can find additional application notes and other resources.