ACS37220LEZATR-100B3 Current Sensor Large Carrier -100A to +100A, 3.3V

The ACS37220 Current Sensor Large Carrier features the ACS37220LEZATR-100B3, which is intended for nominal 3.3 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 “3V3 B10” printed on the bottom side.

This large carrier is suitable for various applications requiring current sensing capabilities. The sensor outputs an analog voltage on VOUT that is centered at 1.65 V and changes by 13.2 mV per amp of input current, with positive current increasing the output voltage and negative current decreasing the output voltage.

The sensor requires a supply voltage of 3.15 V to 3.45 V to be connected across the VDD and GND pads, which are labeled on the bottom silkscreen. The output is not ratiometric, so the zero point and sensitivity are independent of the actual supply voltage.

The optional VOC pin can be used to set the overcurrent fault threshold. An on-board 130 kO resistor between VOC and GND sets the default overcurrent fault threshold to approximately 200% of the nominal sensing range, and an external resistor can be added in parallel between VOC and GND to lower this threshold to between 50% and 200%. The following equation gives the value of this parallel resistor, R_OC, in kO as a function of overcurrent fault threshold percentage P:

R_OC = (130 kO · P) / (197% – P)

For example, to set the overcurrent fault limit to 50% of the nominal sensing range, a 44 kO external resistor can be added between VOC and GND.

As a shortcut, VOC can be connected directly to ground to set the overcurrent fault limit to 100% of the nominal sensing range.

The optional FAULT pin is normally at VDD and is pulled low when the IP current magnitude exceeds the set overcurrent fault threshold in either direction. This pin only asserts while the fault condition is present (it is not latched).

Pololu manufactures these boards in-house at Pololu's Las Vegas facility, which gives Pololu the flexibility to make these current sensors with custom default overcurrent fault thresholds. If you are interested in customization, please contact us.

Making connections to the board

You can insert the board into your current path in a variety of ways. The largest through-holes are 6.4 mm in diameter with 22 mm spacing. These can be used with #12 or M6 screws for attaching various types of lugs or solderless ring terminals, or thick wires up to 4 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.

The FAULT, VOUT, VDD, GND, and VOC pins work with 0.1"-pitch header pins and are compatible with standard solderless breadboards.

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

The dimension diagram is available as a downloadable PDF (403k pdf).

Real-world power dissipation considerations

Depending on the version, the ACS37220 can measure up to ±200 A. However, the sensor chip can overheat at lower currents. In Pololu's tests, Pololu found that Pololu's ACS37220 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 recommends 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 has a variety of current sensors available with different ranges, sensitivities, and features. The table below summarizes Pololu's selection of active and preferred options:

Dimensions

General specifications

Identifying markings

Notes:

1

Typical.

File downloads

• Dimension diagrams of the ACS37220 Current Sensor Carriers (403k pdf)

• 3D model of the ACS37220 Current Sensor Large Carriers (3MB step)

• Drill guide for the ACS37220 Current Sensor Large Carriers (20k dxf)

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

Recommended links

• ACS37220 datasheet

• Allegro product page for the ACS37220 Hall-based Current Sensor

  Allegro product page for the ACS37220, where you can find additional application notes and other resources.