ACS72981LLRATR-100B5 Current Sensor Large Carrier -100A to +100A, 5V

This large carrier features the ACS72981LLRATR-100B5, which is intended for nominal 5 V operation and is designed for bidirectional input current from -100 A to +100 A. This version can be visually distinguished from the other versions by the “5V B10” printed on the bottom side, as shown in the left picture above.

A compact carrier is also available for this sensor IC for more space-constrained applications or to evaluate the IC’s performance with a smaller PCB area for thermal dissipation.

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 is centered at VCC/2 and changes by 20 mV × (VCC/5 V) per amp of input current, with positive current increasing the output voltage and negative current decreasing the output voltage:

VIOUT=VCC2+0.02VA⋅VCC5V⋅IP=VCC⋅(12+IP250A)" role="presentation" style="position: relative;">VIOUT=VCC2+0.02VA·VCC5V·IP=VCC·(12+IP250A)$V_{\text{IOUT}}=\frac{V_{\text{CC}}}{2}+0.02\frac{\text{V}}{\text{A}}·\frac{V_{\text{CC}}}{5\text{V}}·I_{\text{P}}=V_{\text{CC}}·(\frac{1}{2}+\frac{I_{\text{P}}}{250\text{A}})$

IP=250A⋅(VIOUTVCC–12)" role="presentation" style="position: relative;">IP=250A·(VIOUTVCC–12)$I_{\text{P}}=250\text{A}·(\frac{V_{\text{IOUT}}}{V_{\text{CC}}}–\frac{1}{2})$

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. The largest through-holes are 8.4 mm in diameter with 20 mm spacing. These can be used with 5/16" or M8 screws for attaching various types of lugs or solderless ring terminals, or thick wires up to 2 AWG can be soldered directly to the board. The slots near the edge of the board can accommodate a 4-pin terminal block or other connector with a pitch between 7.5 mm and 9.5 mm. Examples of these kinds of connections are shown in the pictures below. Holes with 0.1", 3.5 mm, and 5 mm spacing are also available for connecting male header pins or terminal blocks, but please note that these smaller connection options are generally not suitable for high currents like those this sensor is intended for.

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

ACS72981 Current Sensor Carrier schematic diagram.

The dimension diagram is available as a downloadable PDF (400k pdf).

Real-world power dissipation considerations

Thermal image of a high-current test of a Pololu current sensor carrier (not necessarily this product).

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 Pololu's tests, Pololu found that Pololu's ACS72981 carrier boards could conduct 60 A continuously while staying well below the thermal limit for the IC. Pololu's 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, Pololu 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.

Comparison of the Pololu current sensor carriers

Pololu have a variety of current sensors available with different ranges, sensitivities, and features. The table below summarizes Pololu's selection of active and preferred options:

	ACS711 Current Sensor Carriers	ACS71240 Current Sensor Carriers	ACS724 Current Sensor Carriers	ACS37220 Current Sensor Compact Carriers	ACS37220 Current Sensor Large Carriers	ACS72981 Current Sensor Compact Carriers	ACS72981 Current Sensor Large Carriers	CT432/CT433 TMR Current Sensor Compact Carriers	CT432/CT433 TMR Current Sensor Large 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 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 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 5V Bidirectional: ±20 A / 100 mV/A ±30 A / 66.7 mV/A ±65 A / 30.8 mV/A 5V Unidirectional: 0–?50 A / 80 mv/A 0–?70 A / 57.1 mv/A	3.3V Bidirectional: ±50 A / 20 mV/A 5V Bidirectional: ±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 mO	0.6 mO	0.6 mO	0.1 mO		0.2 mO		1 mO
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⁾ 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.

Dimensions

General specifications

Identifying markings

Notes:

1

At VCC = 5 V.

2

Typical.

File downloads

• Dimension diagrams of the ACS72981xLR Current Sensor Carriers (400k pdf)

• 3D model of the ACS72981xLR Current Sensor Large Carriers (3MB step)

• Drill guide for the ACS72981xLR Current Sensor Large Carriers (19k dxf)

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

Recommended links

• ACS72981 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 ACS72981 Hall-based Current Sensor

  Allegro product page for the ACS72981, where you can find additional application notes and other resources.