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# ACS71240KEXBLT-030B3 Current Sensor Carrier -30A to +30A, 3.3V

**Type:** Product page · **SKU:** POLOLU-5241 · **Brand:** [Pololu](https://core-electronics.com.au/brands/pololu-australia)
**Page:** https://core-electronics.com.au/acs71240kexblt-030b3-current-sensor-carrier-30a-to-30a-33v.html ([markdown](https://core-electronics.com.au/acs71240kexblt-030b3-current-sensor-carrier-30a-to-30a-33v.html.md))

This board is a simple carrier of Allegro’s ACS71240KEXBLT-030B3 Hall effect-based linear current sensor, which offers a low-resistance (~0.6 mO) current...

## Pricing

- **Price:** $8.85 (inc GST) — $8.05 AUD, exc GST
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## Availability & dispatch

- Available with a lead time — expect dispatch between Aug 28 and Aug 31.

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## Description

Pololu is offering these breakout boards with support from Allegro Microsystems as an easy way to use or evaluate their ACS71240 Hall effect-based, electrically isolated current sensors with overcurrent fault output; Pololu therefore recommend careful reading of the [ACS71240 datasheet](https://core-electronics.com.au/attachments/localcontent/acs71240-datasheet_2398422c048.pdf) 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 electrical isolation.
- 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.
- The conductive path internal resistance is typically 0.6 mO, and the PCB is made with 2-oz copper, so very little power is lost in the module.
- High-bandwidth 120 kHz 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.
- Overcurrent fault output with 1.5 µs response time indicates when the current exceeds the optimized sensing range and can be used for fast short-circuit detection.
- 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 125°C.
- 0.7"×0.8" carrier board offers 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.
- Unidirectional and bidirectional versions available.

The pads are labeled on the bottom silkscreen. The silkscreen also shows the direction that is interpreted as positive current flow via the **+i** arrow.

**Details for item #5241**

This carrier features the ACS71240KEXBLT-030B3, which is intended for operation around 3.3 V and is designed for bidirectional input current from -30 A to +30 A. This version can be visually distinguished from the other versions by the “3V3 B30” printed on the bottom side.

**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 3.0 V to 3.6 V to be connected across the VCC and GND pads, which are labeled on the bottom silkscreen. The sensor outputs an analog voltage on VIOUT 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:

VIOUT=1.65V+0.044VA·IP

IP=VIOUT–1.65V0.044VA=(VIOUT–1.65V)·22.7AV

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

The optional FAULT pin is normally at VCC and is pulled low when the IP current magnitude exceeds 30 A in either direction. This pin only asserts while the fault condition is present (it is **not** latched).

The FAULT, VIOUT, VCC, and GND pins work with [0.1"-pitch header pins](https://core-electronics.com.au/0-100-2-54-mm-breakaway-male-header-1x40-pin-straight.html) and are compatible with standard [solderless breadboards](https://core-electronics.com.au/prototyping/breadboards.html).

You can insert the board into your current path in a variety of ways. Holes with 0.1", 3.5 mm, and 5 mm spacing are available for connecting [male header pins](https://core-electronics.com.au/0-100-2-54-mm-breakaway-male-header-1x40-pin-straight.html) or [terminal blocks](https://core-electronics.com.au/catalogsearch/result/?q=terminal%20block). For 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 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. The pictures below show some of the possible connection options:

**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** (274k pdf).

**Real-world power dissipation considerations**

Depending on the version, the ACS71240 can measure up to ±50 A. However, the sensor chip will typically overheat at lower currents. In Pololu's tests, Pololu found that Pololu's ACS71240 carrier board could conduct about 45 A continuously without reaching 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 30 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 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**

| Size: | 0.7" × 0.8" |
|---|---|
| Weight: | 1.1 g |

**General specifications**

| 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: | 12 mA |
| Current range: | -?30A to +30A (bidirectional 30A), 3.3V |
| Current sensor: | Allegro ACS71240KEXBLT-030B3 |

**Identifying markings**

| PCB dev codes: | cs02b |
|---|---|
| Other PCB markings: | 0J7387 |
| Other PCB markings: | 3V3 B30 |

**Notes:**

1Max.**File downloads**

- **Dimension diagram of the ACS71240 Current Sensor Carrier (274k pdf)**
- **3D model of the ACS711EX and ACS71240 Current Sensor Carrier (3MB step)**
- **Drill guide for ACS711EX and ACS71240 Current Sensor Carrier (18k dxf)**
    
    This DXF drawing shows the locations of all of the board’s holes.

**Recommended links**

- **[ACS71240 datasheet](https://core-electronics.com.au/attachments/localcontent/acs71240-datasheet_2398422c048.pdf)**
- **[Allegro Application Note AN296169: Characterizing System Bandwidth in Complex Current Sensor Applications](https://www.allegromicro.com/en/insights-and-innovations/technical-documents/hall-effect-sensor-ic-publications/an-effective-method-for-characterizing-system-bandwidth-an296169)**
    
    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 to 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 ACS71240 Hall-based Current Sensor](https://www.allegromicro.com/en/products/sense/current-sensor-ics/zero-to-fifty-amp-integrated-conductor-sensor-ics/acs71240)**
    
    Allegro product page for the ACS71240, where you can find additional application notes and other resources.

## Images

- [Product image 1](https://core-electronics.com.au/media/catalog/product/P/O/POLOLU-5241-1.jpg)