Summary of Current Sensor Amplifier & Over Current Switch
This project utilizes an ACS714-30A sensor and LM358 Op-amp to create a current amplifier and over-current switch. One half of the LM358 amplifies low-voltage signals, while the other acts as a comparator for high-TTL outputs that trigger when current exceeds a set limit defined by a trimmer potentiometer. The circuit operates on 5V DC, includes an onboard power LED, and features a resistor divider (R1, R3) for microcontroller bus voltage monitoring up to 5V.
Parts used in the Current Sensor Amplifier and Over Current Switch:
- ACS714-30A current sensor
- LM358 Op-amp
- Trimmer potentiometer
- Resistor divider (R1 and R3)
- Onboard LED
Current sensor amplifier and over current switch project is based on ACS714-30A current sensor and LM358 Op-amp, ½ of LM358 op-amp used as an amplifier for low voltage and 2nd 1/2 LM358 op-amp used as comparator which provides over current TTL output, trimmer potentiometer provided to set the over current limit. ACS714 sensor measures the current up to +/-30Amps, final output of the amplifier is 235mV/1A, and normally over current output is High-TTL, its goes low once the current over shoot than a set point. Circuit requires 5V DC and 40mA, Onboard LED indicates the power. Resistor divider R1, R3 provides bus voltage output for micro-controller interface to measure the bus voltage, choose appropriate value for R3, R1 as per your application and bus voltage, it’s should be less than 5V DC.
ACS714 Current Sensor
The Allegro™ ACS714 provides economical and precise solutions for AC or DC current sensing in automotive systems. The device package allows for easy implementation by the customer. Typical applications include motor control, load detection and management, switch-mode power supplies, and overcurrent fault protection. The device consists of a precise, low-offset, linear Hall circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which the Hall IC converts into a proportional voltage. Device accuracy is optimized through the close proximity of the magnetic signal to the Hall transducer. A precise, proportional voltage is provided by the low-offset, chopper-stabilized BiCMOS Hall IC, which is programmed for accuracy after packaging. The output of the device has a positive slope (>VIOUT(Q)) when an increasing current flows through the primary copper conduction path (from pins 1 and 2, to pins 3 and 4), which is the path used for current sampling. The internal resistance of this conductive path is 1.2 mΩ typical, providing low power loss. The thickness of the copper conductor allows survival of the device at up to 5× overcurrent conditions.
Read more: Current Sensor Amplifier & Over Current Switch
- What is the maximum current the ACS714 sensor can measure?
The ACS714 sensor measures current up to +/-30Amps. - How does the circuit indicate an over-current condition?
The over-current output is normally High-TTL and goes low once the current overshoots the set point. - Can this circuit interface with a microcontroller?
Yes, a resistor divider using R1 and R3 provides a bus voltage output for micro-controller interface measurement. - What voltage supply does the circuit require?
The circuit requires 5V DC and consumes 40mA. - How is the over-current limit adjusted?
A trimmer potentiometer is provided to set the over-current limit. - What is the function of the two halves of the LM358 Op-amp?
One half is used as an amplifier for low voltage and the second half is used as a comparator for TTL output. - What does the onboard LED indicate?
The onboard LED indicates the power status. - What is the output slope of the ACS714 device?
The output has a positive slope when increasing current flows through the primary copper conduction path.
