ACS712 Current Sensor User Manual

Basic Overview

ACS 712 on IC StationThe ACS712 Current Sensors offered on the internet are designed to be easily used with micro controllers like the Arduino.

These sensors are based on the Allegro ACS712ELC chip.

These current sensors are offered with full scale values of 5A,  20A and 30A.

The basic functional operation of each of these devices is identical.  The only difference is with the scale factor at the output as detailed below.

Other ACS712 Henry’s Bench Articles

ACS712 Arduino Tutorial Shows how to use the device with an Arduino

ACS712 AC Voltage Measurement  shows how to measure a Sine Wave Voltage with an Arduino

18650 Battery Charger shows another implementation of the ACS712

ACS758 Tutorial  Shows a similar device for monster currents.

How to Get One

If you don’t have one of these modules and think that you may want one, you can try these links. It will only set you back a few dollars.



Bang Good



Sensor Specifications

 5A Module20A Module30A Module
Supply Voltage (VCC)5Vdc Nominal5Vdc Nominal5Vdc Nominal
Measurement Range-5 to +5 Amps-20 to +20 Amps-30 to +30 Amps
Voltage at 0AVCC/2
(nominally 2.5Vdc)
(nominally 2.5Vdc)
(nominally 2.5VDC)
Scale Factor185 mV per Amp100 mV per Amp66 mV per Amp

 ACS712 Module Pin Outs and Connections

The picture below identifies the pin outs for the ACS172 Modules.

Pay attention to the polarity at the load end of the device.   If you are connected as illustrated below, the output will raise.  If you connect it opposite of this picture, the output will decrease from the 2.5 volt offset.

ACS 712 PinoutsBasic Hook Up and Functional Description

As mentioned before, these modules are primarily designed for use with micro-controllers like the Arduino.    In those applications,  the connections would be as picture below:

ACS 712 Basic Hook Up


If the light bulb shown in the picture above were disconnected, the output of the ACS712 module would be 2.500 volts.

Once connected, the output would be scaled to the current drawn through the bulb.   If this were a 5 Amp module and the light bulb pulled 1 Amp, the output of the module would be 2.685 volts.

Now imagine the battery polarity reversed.   Using the same 5A module, the output would be 2.315 volts.

IMPORTANT NOTE –  This device is a Hall Effect transducer.  It should not be used near significant magnetic fields.

ACS712ELC Datasheet

The datasheet below will give you greater insight into the specifications and operation of this manual.

acs712 datasheet


  1. December 5, 2016
  2. Leo December 3, 2016
  3. steven August 21, 2016
  4. July 27, 2016
  5. Philippe July 21, 2016
  6. February 21, 2016
  7. novan February 21, 2016
  8. January 13, 2016
  9. Sameer January 13, 2016
  10. July 9, 2015
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