Current Sensor 20A - ACS712

ACS712 current sensor operates from 5V and outputs analog voltage proportional to current measured on the sensing terminals. You can simple use a microcontroller ADC to read the values.

Sensing terminal can even measure current for loads operating at high voltages like 230V AC mains while output sensed voltage is isolated from measuring part.

Provides up to 3000 VRMS galvanic isolation. The low-profile, small form factor packages are ideal for reducing PCB area over sense resistor op-amp or bulky current transformer configurations. The low resistance internal conductor allows for sensing up to 20 A continuous current. Providing typical output error of 1%.

Features

• 100 mV/A output sensitivity
• 5.0 V, single supply operation
• Output voltage proportional to AC or DC currents
• Factory-trimmed for accuracy
• Extremely stable output offset voltage
• Nearly zero magnetic hysteresis
• Ratiometric output from supply voltage
• Low-noise analog signal path
• Device bandwidth is set via the new FILTER pin
• 5 µs output rise time in response to step input current
• 80 kHz bandwidth
• Total output error 1.5% at TA = 25°C
• Small footprint, low-profile SOIC8 package
• 1.2 mΩ internal conductor resistance
• 2.1 kVRMS minimum isolation voltage from pins 1-4 to pins 5-8

Frequently Asked Questions

Q. What voltage i need to supply to module to power it on?
A. Give regulated +5V to module at its VCC connector.

Q. What is output voltage without any load?
A. It is VCC/2 so it means around 2.5V

Q. What happens to output voltage if i connect a DC load current?
A. When DC load takes current the output voltage will deviate from 2.5V to either 0V or 5V depending on polaity of sensing load.

Q. Does DC load and AC load has same type of output?
A. No. With DC load you can check simply with multimeter, But in case of AC load its totally different. Your multimeter will show same 2.5V output whatever load you put on AC because what happens here is when positive AC phase is going on the output voltage increased from 2.5V and during negative phase the output voltage decreases from 2.5V so your multimeter will average that and show you same voltage. 

Q. How to check AC load output?
A. To check AC load you cannot use multimeter or ADC directly. The output needs to be offset and rectified to read AC load as below.

Solution#1 from Datasheet - Simple rectification

"Rectified Output. 3.3 V scaling and rectification application for A-to-D converters. Replaces current transformer solutions with simpler ACS circuit. C1 is a function of the load resistance and filtering desired. R1 can be omitted if the full range is desired." (from the datasheet)

Solution#2 for AC reading using Opamp with offset