ACS712ELC-20A Current Sensor – Hall-Effect Analog Current Measurement Module for Arduino

The TB-ACS712 current sensor module is based on the ACS712ELC-20A Hall-effect current sensor and provides an analog voltage proportional to current through the measurement path. It is useful for DC motor current monitoring, battery projects, power experiments, and overload detection in Arduino-style systems.

The Allegro ACS712 family provides galvanic isolation between the sensed conductor and low-voltage signal side through Hall-effect measurement. Use it with the ELAB Nano V3, UNO R3 Prototype Expansion Board, or logging projects that combine voltage and current measurement.

For accurate readings, calibrate zero-current offset and keep traces and terminals within the module rating. The 20A variant has a different sensitivity than 5A or 30A ACS712 boards, so use code constants for the correct version.

Technical Specifications

Board Layout & Label Guide

• IP+ / IP- – High-current measurement path terminals.
• VCC – 5V sensor supply.
• GND – Signal ground.
• OUT – Analog output to ADC.
• ACS712 IC – Hall-effect current sensor.
• Current Direction – Output increases or decreases depending on current direction.
• Calibration Note – Measure zero-current offset before use.
• Safety Note – Keep current and voltage within module limits.

Application Scenarios

1. Arduino Current Read

Read analog output and convert using a 20A ACS712 sensitivity estimate.

const int currentPin = A0;const float vcc = 5.0;const float sensitivity = 0.100;void setup() { Serial.begin(115200);}void loop() { int adc = analogRead(currentPin); float voltage = adc * vcc / 1023.0; float current = (voltage – vcc / 2.0) / sensitivity; Serial.println(current); delay(500);}

2. Zero Offset Calibration

Average ADC readings with no current flowing.

long total = 0;void setup() { Serial.begin(115200); for (int i = 0; i < 500; i++) { total += analogRead(A0); delay(2); } Serial.println(total / 500.0);}void loop() {}

3. Overcurrent Alarm

Trigger an LED when measured current exceeds a threshold.

const int ledPin = 13;void setup() { pinMode(ledPin, OUTPUT);}void loop() { int adc = analogRead(A0); digitalWrite(ledPin, adc > 650 || adc < 374 ? HIGH : LOW); delay(100);}

Packing List

• 1 x ACS712ELC-20A Current Sensor Module

FAQ

Q: What current version is this?
A: The title identifies ACS712ELC-20A, the 20A variant.

Q: Is output digital?
A: No, it is analog.

Q: Can it measure bidirectional current?
A: Yes, ACS712-style output is centered around VCC/2.

Q: Do I need calibration?
A: Yes, zero-current offset calibration improves accuracy.

Q: Can it measure AC current?
A: It can sense bidirectional current, but RMS calculation is required for AC.

Q: What ADC voltage should I expect at zero current?
A: Approximately half the supply voltage.

Q: Can I exceed 20A?
A: No, stay within module and connector limits.

Q: Is it isolated?
A: The Hall-effect sensor provides isolation between conductor and signal side within IC ratings.