Electronics

Current Sensor Module MAX471 DC Red/Black

AED 22.00

Low stock
1

Description

The MAX471 modules feature the MAX471 IC, a highly capable component designed for accurate current measurement of up to 3 amps. Utilizing a 35 milliohm shunt resistor internally, the module channels the current to be measured effectively. The MAX471 IC amplifies the voltage drop across the shunt and provides the amplified signal through the OUT pin. Notably, the OUT voltage remains positive, regardless of the direction of the current flow. This module offers reliable and precise current measurement capabilities for various applications requiring current monitoring and control.

 

Package Includes:

  • 1x Current Sensor Module MAX471 DC

 

Features:

  • Monitors Both Charge and Discharge: The module is capable of monitoring current in both charging and discharging modes, making it suitable for applications involving battery management or energy flow control.
  • Complete High-Side Current Sensing: It provides high-side current sensing, allowing for accurate measurement of current without the need for additional circuitry or complex configurations.
  • Precision Internal Sense Resistor: The module incorporates a precision internal sense resistor, ensuring accurate current measurement with minimal errors.
  • Sense Capability with Internal Sense Resistor (MAX471): The MAX471 variant of the module offers a 3A sense capability, making it suitable for applications where moderate current sensing is required.
  • Higher Current-Sense Capability with External Sense Resistor (MAX472): The MAX472 variant of the module provides the flexibility to use an external sense resistor, enabling higher current-sensing capabilities beyond the 3A range.
  • Vast Range of Applications: The module finds applications in various fields, including battery management systems, power supplies, motor control, energy monitoring, and other energy management applications.

 

Description:

The MAX471 Sensor Module, is a versatile and powerful current sensing solution. The module incorporates an IC that accepts input voltages spanning from 3V to 36V, making it compatible with a wide range of power sources. With its precision sensing resistor and two securely connected Blue color terminals, the MAX471 ensures accurate and reliable current measurements. Specifically designed to measure currents up to 3 amps, the module employs a 35 milliohm shunt resistor to effectively channel the current for measurement. The RS- and RS+ pins are intelligently integrated into these terminals, enhancing the module's connectivity and usability. By amplifying the voltage drop across the shunt, the MAX471 delivers a highly amplified and dependable signal through the OUT pin, facilitated by its four-pin configuration. Importantly, regardless of the current direction, the voltage output at the OUT pin remains consistently positive. This module is the ideal choice for applications requiring precise current monitoring and control, such as battery management systems, power supplies, motor control, and energy monitoring. With its wide input voltage range and advanced features, the MAX471 Sensor Module empowers engineers and enthusiasts to achieve optimal energy management and efficient current sensing in a vast array of electronic projects.

 

Principle of Work:

  1. Current Sensing: The modules utilize a high-side current sensing technique. They are designed to measure the current flowing through a load or a battery by sensing the voltage drop across a small, internal current-sense resistor.
  2. Internal Sense Resistor: The MAX471 module incorporates an internal 35m (milliohm) current-sense resistor. This resistor is connected in series with the load or battery being monitored. The voltage drop across this resistor is proportional to the current flowing through it.
  3. Current Amplification: Once the voltage drop across the internal sense resistor is obtained, the MAX471/MAX472 amplify this voltage using an internal amplifier. The amplified voltage represents the current being measured.
  4. Output and Conversion: Both modules provide a current output that can be converted to a ground-referred voltage using a single external resistor. By selecting an appropriate resistor, the current output can be converted into a voltage output that is proportional to the current being measured.
  5. The direction of Current Flow: The modules also include an open-collector SIGN output. This output provides information about the direction of the current flow. It allows the user to determine whether the battery or load is being charged or discharged based on the output's logic level.
  6. Voltage and Current Range: The MAX471 and MAX472 modules operate within a voltage range of 3V to 36V. They are capable of measuring currents up to 3A (MAX471) or higher currents with the use of external sensors and gain-setting resistors (MAX472).

By utilizing high-side current sensing, incorporating an internal sense resistor, and providing amplification and conversion capabilities, the MAX471 and MAX472 modules offer a comprehensive solution for accurate and efficient current monitoring in battery-powered systems and other applications that require precise current measurements.

Pinout of the Board:

The module utilizes VIN and VOUT for current connections. Signal 1 (AT) generates the output current directly, while Signal 2 (VT) is created using a voltage divider circuit connected to Signal 1, with specific resistors (30 kOhm and 7.5 kOhm) incorporated on the module.

The module has two current connections: VIN (Input Voltage) and VOUT (Output Voltage).

  • Signal 1, represented as AT, has a voltage-to-current ratio of 1 Volt per ampere. When applied to the module, it generates the desired output current.
  • Signal 2, represented as VT, has a voltage-to-current ratio of 0.2 Volts per ampere. It is produced by a voltage divider circuit on the module, using Signal 1 as the input. The voltage divider consists of two resistors: a 30 kOhm resistor and a 7.5 kOhm resistor. These resistors are visibly present on the module.

 

Applications:

  1. Battery Management: The module is utilized in battery-powered devices, such as smartphones, laptops, and portable electronics, to monitor battery charging and discharging currents, enabling efficient battery management.
  2. Power Supplies: It is used in power supply systems to measure and regulate current flow, ensuring safe and reliable operation.
  3. Motor Control: The module finds application in motor control systems to monitor and adjust the current supplied to motors, enabling precise control and protection against overload conditions.
  4. Energy Monitoring: It is employed in energy monitoring systems to track and analyze current consumption, enabling energy-efficient operation and optimization of energy usage.
  5. Industrial Automation: The module is utilized in industrial automation systems to monitor and control current in machinery, providing valuable insights for maintenance, fault detection, and process optimization.
  6. Automotive Electronics: It finds applications in automotive systems to monitor current in various circuits, such as lighting systems, power distribution, and motor control, ensuring proper functioning and safety.
  7. IoT Devices: The module is used in Internet of Things (IoT) devices for current monitoring and control, enabling data-driven decision-making and efficient energy usage.

 

Circuit:

The module utilizes the analog input A0 to read the OUT signal. The SIGN pin is an open collector input, which means it can be either closed or open depending on the direction of the current flow. To test this functionality, you can connect a pull-up resistor and use digitalRead to check the state. When the current flows from RS+ to RS-, the SIGN pin is closed, indicated by a HIGH or 1 reading. On the other hand, when the current flows in the opposite direction, the SIGN pin is open.

Regarding the alternative red module, it follows a similar wiring configuration. However, it is commonly preferred to use the more sensitive AT output rather than VT. This sensitivity difference can influence the choice of which output to utilize for current monitoring applications.

Library: 

No Library is needed for the module to function

 

Code:

In our setup, the current sensor plays a crucial role in calculating the power consumption (P) of the consumer. To determine the power, you only need to measure the voltage across the consumer's V+ connection. The current sensor provides the necessary information about the current flowing through the system, commonly referred to as the bus current. With these measurements, we can accurately calculate and monitor the power usage of the consumer.

const int outPin = A0; // Analog pin for voltage measurement
const int busPin = A1; // Analog pin for bus voltage measurement
const int signPin = 8; // Digital pin for current direction indication

void setup() {
Serial.begin(9600);
Serial.println("MAX471 Current and Power Sensor");
Serial.println();
}

void loop() {
float voltage = 0.0; // Variable to store voltage value
unsigned long rawVal = 0; // Variable to store raw analog readings

analogReference(INTERNAL); // Set internal reference voltage

// Dummy analogRead and delay to stabilize readings
rawVal = analogRead(outPin);
rawVal = 0;
delay(10);

for(int i=0; i<25; i++){ // Average multiple readings to reduce noise
rawVal += analogRead(outPin);
delay(10);
}

voltage = (rawVal/25.0) * 1100.0 / 1023.0; // Convert raw readings to voltage in mV
Serial.print("Voltage Out [mV]: ");
Serial.println(voltage);

float current_mA = voltage * 0.9452 + 1.0544; // Apply calibration parameters for current calculation
Serial.print("Bus Current [mA]: ");
Serial.println(current_mA);

Serial.print("Current Direction: ");
if(digitalRead(signPin)){ // Check the digital pin for current direction
Serial.println("RS+ -> RS-");
}
else{
Serial.println("RS- -> RS+");
}

analogReference(DEFAULT); // Reset reference voltage

voltage = analogRead(busPin) * 5.0 / 1023.0; // Read bus voltage and convert to actual voltage value
Serial.print("Bus Voltage [V]: ");
Serial.println(voltage);

float power_mW = (voltage * current_mA); // Calculate power in mW
Serial.print("Power [mW]: ");
Serial.println(power_mW);

Serial.println("-------------------------------");
delay(2000); // Delay between readings
}

You should see an output in the serial monitor.

  • The module uses analog pin A0 (outPin) to measure the voltage, and A1 (busPin) to measure the bus voltage.
  • Digital pin 8 (signPin) is used to indicate the current direction.
  • In the setup function, we initialize the serial communication and print a message to identify the module.
  • The loop function continuously reads and processes the data.
  • It first stabilizes the readings by performing a dummy analogRead and introducing a short delay.
  • Then, it takes multiple analog readings to reduce noise and calculates the voltage using calibration parameters.
  • The voltage is converted to the bus current using another set of calibration parameters.
  • The current direction is determined by checking the state of the digital signPin.
  • The module's reference voltage is reset, and the bus voltage is read and converted to an actual voltage value.
  • Power is calculated by multiplying the bus voltage with the current.
  • Finally, the results are printed via serial communication.
  • A delay of 2 seconds is added between readings for proper timing.

 

Technical Details:

  • Current sens max: +/- 3A
  • 100µA Max Supply Current
  • 18µA Max Shutdown Mode
  • Current sense voltage: 3 to 36V
  • Sensor output: 1V / Amp
  • Dimensions: 20mm x 19.5mm

 

Resources:

 

Comparisons:

The MAX471 and ACS712 are both current sensing modules used for measuring current in electronic systems:

  1. Principle: The MAX471 is a high-side current-sense amplifier that measures the voltage drop across an internal sense resistor, while the ACS712 is a hall-effect based current sensor that detects the magnetic field generated by the current.
  2. Current Range: The MAX471 is designed to measure currents up to 3A with an internal sense resistor, whereas the ACS712 is available in different variants with current ranges ranging from a few amperes to several tens of amperes.
  3. Sensitivity: The ACS712 offers a higher sensitivity compared to the MAX471, enabling more accurate current measurements.
  4. Calibration: The MAX471 requires calibration to convert the voltage reading to the corresponding current, while the ACS712 provides a linear output voltage that directly corresponds to the sensed current, eliminating the need for calibration.
  5. Connection: The MAX471 typically requires a low-side connection, while the ACS712 allows for both low-side and high-side connections, providing flexibility in the circuit design.
  6. Noise Immunity: The ACS712's hall-effect sensing technology offers better noise immunity compared to the MAX471, making it suitable for applications where noise rejection is critical.
  7. Isolation: The ACS712 is available in isolated versions, allowing for enhanced safety and isolation between the current path and the measuring circuit. The MAX471 does not have built-in isolation.
  8. Applications: The MAX471 is commonly used in battery management systems, power supplies, motor control, and energy monitoring applications. The ACS712 finds applications in motor control, power management, renewable energy systems, and industrial automation.