This is the compact version of a simple carrier for Allegro’s ACS72981ELRATR-200B3 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.
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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:
The connection points are labelled 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 (V) |
Current Range | Sensitivity @ Nominal Vcc (mV/A) |
Zero Point @ Nominal Vcc (V) |
Size | Price | ||
---|---|---|---|---|---|---|---|---|---|
Large Carrier |
#5270 | 050B3 | 3.0 to 3.6 (3.3 nominal) |
Bidirectional | ±50 A | 26.4 | 1.65 | 1.4″×1.2″ | $12.95 |
#5273 | 100B3 | ±100 A | 13.2 | ||||||
#5277 | 150B3 | ±150 A | 8.8 | ||||||
#5281 | 200B3 | ±200 A | 6.6 | ||||||
#5272 | 050U3 | Unidirectional | 0-50 A | 52.8 | 0.33 | ||||
#5275 | 100U3 | 0-100 A | 26.4 | ||||||
#5279 | 150U3 | 0-150 A | 17.6 | ||||||
#5283 | 200U3 | 0-200 A | 13.2 | ||||||
#5271 | 050B5 | 4.5 to 5.5 (5 nominal) |
Bidirectional | ±50 A | 40 | 2.5 | |||
#5274 | 100B5 | ±100 A | 20 | ||||||
#5278 | 150B5 | ±150 A | 13.3 | ||||||
#5282 | 200B5 | ±200 A | 10 | ||||||
#5276 | 100U5 | Unidirectional | 0-100 A | 40 | 0.5 | ||||
#5280 | 150U5 | 0-150 A | 26.7 | ||||||
Compact Carrier |
#5250 | 050B3 | 3.0 to 3.6 (3.3 nominal) |
Bidirectional | ±50 A | 26.4 | 1.65 | 0.7″×0.8″ | $9.95 |
#5253 | 100B3 | ±100 A | 13.2 | ||||||
#5257 | 150B3 | ±150 A | 8.8 | ||||||
#5261 | 200B3 | ±200 A | 6.6 | ||||||
#5252 | 050U3 | Unidirectional | 0-50 A | 52.8 | 0.33 | ||||
#5255 | 100U3 | 0-100 A | 26.4 | ||||||
#5259 | 150U3 | 0-150 A | 17.6 | ||||||
#5263 | 200U3 | 0-200 A | 13.2 | ||||||
#5251 | 050B5 | 4.5 to 5.5 (5 nominal) |
Bidirectional | ±50 A | 40 | 2.5 | |||
#5254 | 100B5 | ±100 A | 20 | ||||||
#5258 | 150B5 | ±150 A | 13.3 | ||||||
#5262 | 200B5 | ±200 A | 10 | ||||||
#5256 | 100U5 | Unidirectional | 0-100 A | 40 | 0.5 | ||||
#5260 | 150U5 | 0-150 A | 26.7 |
Alternatives available with variations in these parameter(s): typical operating voltage current range size Select variant…
This compact carrier features the ACS72981ELRATR-200B3, which is intended for nominal 3.3 V operation and is designed for bidirectional input current from -200 A to +200 A. This version can be visually distinguished from the other versions by the “3V3 B20” 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 |
---|---|---|---|---|---|
200B3 | ±200 A (bidirectional) | 3.0 V to 3.6 V | 6.6 mV/A | 1.65 V | 0.7″×0.8″ |
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 labelled on the bottom silkscreen. The sensor outputs a ratiometric analogue voltage on VIOUT that is centred at VCC/2 and changes by 6.6 mV × (VCC/3.3 V) per amp of input current, with positive current increasing the output voltage and negative current decreasing the output voltage:
``V_"IOUT" = V_"CC" / 2 + 0.0066 text(V)/text(A) * V_"CC" / (3.3 text(V)) * I_"P" = V_"CC" * (1/2 + I_"P" / (500 text(A)))``
``I_"P" = 500 text(A) * (V_"IOUT" / V_"CC" – 1/2)``
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.
The dimension diagram is available as a downloadable PDF (400k pdf).
Thermal image of a high-current test of a Pololu current sensor carrier (not necessarily this product). |
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Depending on the version, the ACS72981 can measure up to ±200 A, but its datasheet specifies an absolute maximum continuous current of 120 A. Furthermore, the sensor chip can overheat at lower currents. In our tests, we found that our ACS72981 carrier boards could conduct 60 A continuously while staying well below the thermal limit for the IC. Our tests were conducted at approximately 25°C ambient temperature with no forced air flow.
The actual current you can pass through the sensor will depend on how well you can keep it cool. The carrier’s printed circuit board is designed to help with this by drawing heat out of the sensor chip. Solid connections to the current path pins (such as with thick soldered wires or large, tightly-secured lugs) can also help reduce heat build-up in the sensor and carrier board.
Warning: Exceeding temperature or current limits can cause permanent damage to the sensor. If you are measuring an average continuous current greater than 50 A, we strongly recommend that you monitor the sensor’s temperature and look into additional cooling if necessary.
This product can get hot enough to burn you long before the chip overheats. Take care when handling this product and other components connected to it.
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 | ACS37220Current SensorCompact Carriers | ACS37220Current SensorLarge Carriers | ACS72981Current SensorCompact Carriers | ACS72981Current SensorLarge Carriers | CT432/CT433 TMRCurrent SensorCompact Carriers | CT432/CT433 TMRCurrent SensorLarge Carriers | |
---|---|---|---|---|---|---|---|---|---|
Sensor IC | Allegro ACS711KEXT |
Allegro ACS71240 |
Allegro ACS724LLCTR |
Allegro ACS37220 | Allegro ACS72981xLR | Allegro CT432/CT433 | |||
Sensing technology | Hall effect | Hall effect | Hall effect | Hall effect | Hall effect | XtremeSense™ TMR (tunneling magnetoresistance) |
|||
Logic voltage range (V) | 3.0–5.5 | 3.3V versions: 3.0–3.6 5V versions: 4.5–5.5 |
4.5–5.5 | 3.3V versions: 3.15–3.45 5V versions: 4.5–5.5 |
3.3V versions: 3.0–3.6 5V versions: 4.5–5.5 |
3.3V versions: 3.0–3.6 5V versions: 4.75–5.5 |
|||
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 Bidirectional: ±10 A / 200 mV/A ±30 A / 66 mV/A ±50 A / 40 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: ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A 5V Bidirectional: ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A |
3.3V Bidirectional: ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A 5V Bidirectional: ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A |
3.3V Bidirectional:(1) ±50 A / 26.4 mV/A ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A ±200 A / 6.6 mV/A 3.3V Unidirectional:(1) 0–50 A / 52.8 mv/A 0–100 A / 26.4 mv/A 0–150 A / 17.6 mv/A 0–200 A / 13.2 mv/A 5V Bidirectional:(2) ±50 A / 40 mV/A ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A 5V Unidirectional:(2) 0–100 A / 40 mv/A 0–150 A / 26.7 mv/A |
3.3V Bidirectional:(1) ±50 A / 26.4 mV/A ±100 A / 13.2 mV/A ±150 A / 8.8 mV/A ±200 A / 6.6 mV/A 3.3V Unidirectional:(1) 0–50 A / 52.8 mv/A 0–100 A / 26.4 mv/A 0–150 A / 17.6 mv/A 0–200 A / 13.2 mv/A 5V Bidirectional:(2) ±50 A / 40 mV/A ±100 A / 20 mV/A ±150 A / 13.3 mV/A ±200 A / 10 mV/A 5V Unidirectional:(2) 0–100 A / 40 mv/A 0–150 A / 26.7 mv/A |
3.3V Bidirectional: ±20 A / 50 mV/A ±30 A / 33.3 mV/A ±50 A / 20 mV/A ±70 A / 14.3 mV/A 3.3V Unidirectional: 0–20 A / 100 mv/A 0–30 A / 66.7 mv/A 0–50 A / 40 mv/A 0–65 A / 30.8 mv/A 5V Bidirectional: ±20 A / 100 mV/A ±30 A / 66.7 mV/A ±50 A / 40 mV/A ±65 A / 30.8 mV/A 5V Unidirectional: 0–20 A / 200 mv/A 0–30 A / 133.3 mv/A 0–50 A / 80 mv/A 0–70 A / 57.1 mv/A |
3.3V Bidirectional: ±50 A / 20 mV/A ±70 A / 14.3 mV/A 3.3V Unidirectional: 0–50 A / 40 mv/A 0–65 A / 30.8 mv/A 5V Bidirectional: ±50 A / 40 mV/A ±65 A / 30.8 mV/A 5V Unidirectional: 0–50 A / 80 mv/A 0–70 A / 57.1 mv/A |
IC path resistance | 0.6 mΩ | 0.6 mΩ | 0.6 mΩ | 0.1 mΩ | 0.2 mΩ | 1 mΩ | |||
PCB | 2 layers, 2-oz copper |
2 layers, 2-oz copper |
2 layers, 2- or 4-oz copper(4) |
2 layers, 2-oz copper |
6 layers, 2-oz copper |
6 layers, 2-oz copper |
6 layers, 2-oz copper |
2 or 4 layers(5), 2-oz copper |
6 layers, 2-oz copper |
Max bandwidth | 100 kHz | 120 kHz | 120 kHz(3) | 150 kHz | 250 kHz | 1 MHz | |||
Size | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 0.7″ × 0.8″ | 1.4″ × 1.2″ | 0.7″ × 0.8″ | 1.4″ × 1.2″ | 0.8″ × 1.1″ | 1.4″ × 1.2″ |
Overcurrent fault output | User-configurable threshold | ||||||||
Common-mode field rejection | |||||||||
Non-ratiometric output | |||||||||
1-piece price | $3.49 | $3.95 | $6.95 – $7.49 | $4.95 | $7.95 | $9.95 | $12.95 | $8.95 | $12.95 |
(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.
(4) ±50A version uses 4-oz copper PCB; all other versions use 2-oz copper.
(5) 50A and higher versions use 4-layer PCB; all other versions use 2-layer PCB.
You can also use the following selection box to see all these options sorted by current range:
Alternatives available with variations in these parameter(s): current range Select variant…
Size: | 0.7″ × 0.8″ |
---|---|
Weight: | 1.4 g |
Typical operating voltage: | 3.3 V |
---|---|
Current sense: | 6.6 mV/A1 |
Minimum logic voltage: | 3.0 V |
Maximum logic voltage: | 3.6 V |
Supply current: | 14 mA2 |
Current range: | -200A to +200A (bidirectional 200A) |
Current sensor: | Allegro ACS72981ELRATR-200B3 |
PCB dev codes: | cs04a |
---|---|
Other PCB markings: | 0J14752 |
Other PCB markings: | 3V3 B20 |
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 ACS72981, where you can find additional application notes and other resources.