ACS724 Current Sensor Carrier -30A to +30A

This current sensor is a carrier board or breakout board for Allegro’s ACS724LLCTR Hall effect-based linear current sensors; Pololu therefore recommend careful reading of the ACS724 datasheet (2MB pdf) 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) does not affect the measurement.
• The conductive path internal resistance is typically 1.2 mO, 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 (up to 2.4 kV RMS), which allows the sensor to be inserted anywhere along the current path and to be used in applications that require electrical isolation.
• High 120 kHz bandwidth for faster response times in control applications.
• Optional FILTER pin simplifies bandwidth limiting for better noise reduction and improved resolution at lower frequencies.
• 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 150°C.

The pads are labeled on the bottom silkscreen, as shown in the picture to the right. The silkscreen also shows the direction that is interpreted as positive current flow via the +i arrow.

A variety of options are available with different current sensing ranges and sensitivities:

These versions all look very similar, and while you can distinguish them by reading the text on the IC, Pololu also provide a white box on the bottom silkscreen where you can add your own distinguishing markings if so desired.

Details for item #4047

ACS724 Current Sensor Carrier -30A to +30A, top view.

ACS724 Current Sensor Carrier -30A to +30A with included 0.1" header pins.

This carrier features the ACS724LLCTR-30AB, which operates at 5 V and is designed for bidirectional input current from -30 A to +30 A. When Vcc is 5 V, the output voltage is centered at 2.5 V and changes by 66 mV per amp of input current, with positive current increasing the output voltage and negative current decreasing the output voltage.

This board ships assembled with all surface mount components, and a 3×1 strip of 0.1" header pins is included but not soldered in.

Using the sensor

This sensor has five required connections: the input current (IP+ and IP-), logic power (VCC and GND), and the sensor output (OUT).

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, and the sensor outputs an analog voltage that is linearly proportional to the input current.

The FILTER pin lets you adjust the board’s bandwidth by adding a capacitor to ground (a ground pad has been added next to the FILTER pin for convenience) in parallel with the 1 nF capacitor that is already on the board. Without an added external filter capacitor, the bandwidth is about 90 kHz. The datasheet provides more information on how the filter capacitors affect bandwidth.

You can insert the board into your current path in a variety of ways. For low-current applications, you can solder 0.1" male header pins to the board via the smallest pair of through-holes on the input-current side of the board. For higher-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 pair of through-holes are big enough for #6 screws.

ACS7x4/ACHS-712x Current Sensor Carrier soldered with high-current wires.

ACS7x4/ACHS-712x current sensor carrier with solderless ring terminal connectors (not included).

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 protective gear.

Schematic and dimension diagrams

Schematic diagram of the ACS724 Current Sensor Carrier.

The dimension diagram is available as a downloadable PDF (323k pdf).

Comparison of the Pololu current sensor carriers

Pololu have a variety of current sensors available with different ranges, sensitivities, and features. You can use the following table to compare Pololu's options:

	ACS711EX Current Sensor Carriers	ACHS-712x Current Sensor Carriers	ACS724 Current Sensor Carriers	ACS709 Current Sensor Carrier
Sensor IC:	Allegro ACS711KEXLT	Broadcom ACHS-712x	Allegro ACS724LLCTR	Allegro ACS709LLFTR-35BB
Current range / sensitivity(1):	Bidirectional: ±15.5 A / 136 mV/A ±31 A / 68 mV/A	Bidirectional: ±10 A / 185 mV/A ±20 A / 100 mV/A ±30 A / 66 mV/A ±40 A / 50 mV/A ±50 A / 40 mV/A	Unidirectional: 0–?5 A / 800 mv/A 0–?10 A / 400 mv/A 0–?20 A / 200 mv/A 0–?30 A / 133 mV/A Bidirectional: ±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	Bidirectional: ±75 A / 28 mV/A
Path resistance:	0.6 mO	0.7 mO	1.2 mO	1.1 mO
Max bandwidth:	100 kHz	80 kHz(2)	120 kHz(2)	120 kHz(2)
Vcc range:(1)	3 V–5.5 V	4.5 V–5.5 V	4.5 V–5.5 V	3 V–5.5 V
Size:	0.7" × 0.8"	0.7" × 0.8"	0.7" × 0.8"	0.82" × 0.9"
Special features:	over-current fault pin		differential Hall sensing rejects common-mode fields for higher accuracy, integrated digital temperature compensation	configurable over-current threshold
1-piece price:	$3.95	$6.95	$11.95	$14.95
(1) Sensitivity shown for Vcc = 5V.
(2) Bandwidth can be reduced by adding a filter capacitor.

Dimensions

General specifications

Identifying markings

Notes:

1

When Vcc is 5 V.

2

Max. 10 mA typical.

File downloads

• Allegro ACS724 current sensor datasheet (2MB pdf)

• Dimension diagram of the ACS7x4 Current Sensor Carriers (323k pdf)

• 3D model of the ACS7x4 Current Sensor Carriers (3MB step)

• Drill guide for ACS7x4/ACS715 Current Sensor Carriers (42k dxf)

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

• Allegro Application Note AN296169: Characterizing System Bandwidth in Complex Current Sensor Applications (1MB pdf)

  This is the application note referenced on page 16 of the ACS724 datasheet. The ACS720 is used validate the test methods presented, but these same methods and principles would also apply to the ACS724.