This is the larger version of a simple carrier for Allegro’s ACS37042KLHBLT-030B3 Hall effect-based, electrically isolated current sensor in a 5-pin SOT-23 package with ~1.6 mΩ current path resistance and 150 kHz bandwidth.

We are offering these breakout boards with support from Allegro Microsystems as an easy way to use or evaluate their ACS37041 and ACS37042 Hall effect-based, electrically isolated current sensors; we therefore recommend careful reading of the ACS37041/2 datasheet before using this product. The following list details some of the sensor’s key features:

• Hall effect-based sensor with electrically isolated current path allows the sensor to be inserted anywhere along the current path and to be used in applications that require galvanic isolation.
• Low primary current path resistance of 1.6 mΩ in the sensor IC, so very little power is lost in the module.
• 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) has less effect on the measurement.
• 150 kHz bandwidth analog output voltage proportional to AC or DC currents.
• Less than 5 µs response time.
• Output is not ratiometric (i.e. the zero point and sensitivity are independent of the actual supply voltage), which provides immunity from noisy supplies.
• Integrated temperature compensation circuitry allows improved accuracy over the full operating temperature range.
• Automotive-grade operating temperature range of -40°C to 125°C.
• Carrier boards, available in micro (0.3″×0.4″) and our standard compact (0.7″×0.8″) sizes, offer a variety of ways to insert it into the current path along with 0.1″-pitch (breadboard-compatible) power, ground, and output pins.
• 3.3V and 5V versions available.
• ACS37042 ICs have a higher isolation rating and are on PCBs with routed slots for higher creepage.

The connection points and the direction interpreted as positive current flow are labeled on the bottom silkscreen.

Details for item #5455/5457

 

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

Using the Sensor:

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

The sensor requires a supply voltage of 3.0 V to 3.6 V to be connected across the VDD and GND pads, which are labeled on the bottom silkscreen. The sensor outputs an analog voltage on VOUT that is centered at 1.65 V and changes by 44 mV per amp of input current, with positive current increasing the output voltage and negative current decreasing the output voltage:

VOUT=1.65V+0.044VA⋅IP

IP=VOUT–1.65V0.044VA=(VOUT–1.65V)⋅22.7AV

The output is not ratiometric, so the zero point and sensitivity are independent of the actual supply voltage.

Making connections to the board:

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. The largest through-holes are big enough for 10 AWG wires or #6 or M3.5 screws, and the second-largest through-holes (and mounting holes) are sized for 14 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. The pictures below show examples of various connection options with the ACS37220 compact carrier, which has the same physical dimensions as the ACS37041/ACS37042 compact carrier.

The VOUT, VDD, and GND pins work with 0.1″-pitch header pins and are compatible with standard solderless breadboards

Isolation rating and board creepage considerations

The ACS37041 and ACS37042 differ in their manufacturer-rated isolation voltages of 100 VRMS and 285 VRMS, respectively. Both IC packages have a creepage of 1.6 mm, and our ACS37042 carrier PCB has a routed slot under the IC to provide a PCB creepage of 3.0 mm. (The PCB creepage on the ACS37041 carrier is the same 1.6 mm as the IC package itself.) A rough rule of thumb is that uncontaminated FR4 PCBs should have roughly 1 mm of creepage per 100 VRMS of isolation. Please note that these carrier boards are not certified to any particular safety standard.

Warning: This product is generally intended for use below 30 V, and many of the application example pictures (e.g. use on a breadboard) are appropriate for such lower-voltage applications. These boards can be used at higher voltages, but 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:

Real-world power dissipation considerations:

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

In our tests, we found that the micro carrier boards (cs08a and cs08c) could conduct about 25 A continuously, and compact carrier boards (cs08b and cs08d) could conduct about 30 A continuously, without reaching 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 20 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.

Comparison of the Pololu current sensor carriers

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:

Specifications:

• Size : 0.7″ × 0.8″
• Weight : 1.0 g
• Typical operating voltage: 3.3 V
• Current sense : 44 mV/A
• Minimum logic voltage : 3.0 V
• Maximum logic voltage : 3.6 V
• Supply current : 8 mA1
• Current range : -​30A to +30A (bidirectional 30A), 3.3V
• Current sensor : Allegro ACS37042KLHBLT-030B3
• Base IC : ACS37042
• PCB dev codes : cs08d
• Other PCB markings : 0J15457
• Other PCB markings : 3V3 B30

Documentations:

• Wiki

Package Includes:

• 1 x Pololu 5455/5457 ACS37042KLHBLT-030B3 Current Sensor Compact Carrier -30A to +30A, 5V/3.3V