ACS712 Current Sensors
ACS712 is a low cost, precise and Isolated Current measurement sensor from Allegro. The ACS712 Linear Current sensor can be used to measure AC current as well as DC current. The IC basically comes in Surface Mount SOIC8 package.
Since ACS712 works on the principal of Hall Effect the terminals of the conductive path are electrically isolated from the signal leads. The sensor provides 2.1 kVRMS isolation voltage between the measuring part and your circuit. Thus ACS712 can be used in applications which require electrical isolation. The IC basically comes in Surface Mount SOIC8 package thus making it very compact to use in your product. It also has just 1.2 mili ohm internal conductor resistance thereby providing low power losses.
The output voltage of the ACS712 current sensor is Linear. The output voltage of the IC is directly proportional to the primary current. ACS712 IC works on 5 volts. The output of the ACS712 is analog Vout can be measured using any ADC. At no load the output of the current sensor is 2.5 volts and as the current increases and depending on the direction of the measured current the output voltage Increases or Decreases.
At no load the output voltage will be 2.5 volts. When the load current (current that needs to be measured) is flowing IP+ to IP- then the output voltage will increase and if the load current if flowing in reverse direction i.e. from IP- to IP+ then Vout will decrease. So from measuring the output voltage you can measure the current flowing as well as direction of current.
ACS712 Module
The ACS712 Sensor Module is easily available in market. You can buy these ACS712 current Sensor modules at low cost and use it directly in your projects/products.
TYPES OF ACS712 Sensor Modules
Three different types of ACS712 Current sensor modules are available. The classification is based on the maximum load current that can be measured.
You can use this to measure AC and DC current upto 5 ampere. It has a sensitivity of 185mv/Ampere.
You can use this to measure AC and DC current upto 20 ampere. It has a sensitivity of 100mv/Ampere.
You can use this to measure AC and DC current upto 30 ampere. It has a sensitivity of 66mv/Ampere.
So depending upon maximum current that you have to measure and the resolution that you require you can select which module you require. Another main advantage of this sensor is that it can survive 5x times the overcurrent conditions.