Overcurrent Protection with MOSFETs – Schematic Circuit Diagram
Electronic circuits must have overcurrent protection to guard against harm from high current flow. Due to their quick switching times and low on-resistance, MOSFETs (Metal-Oxide Semiconductor Field-Effect Transistors) can be employed as switches in overcurrent protection circuits. In this article, we’ll talk about a straightforward schematic circuit diagram for MOSFET-based overcurrent prevention.
- Sense Resistor (Rs): This resistor, which measures the current flowing through the circuit, is linked in series with the load.
- Comparator (Op-Amp): The voltage across the sense resistor is compared to a reference voltage using the Op-Amp.
- Reference Voltage (Vref): The threshold for overcurrent detection is a preset voltage. The comparator’s output will change state when the voltage across the sense resistor is greater than the reference voltage.
- MOSFET (N-channel): The switch in the circuit is this MOSFET. The MOSFET is turned on when the comparator’s output is high, essentially cutting off the load from the power source.
The voltage that the sense resistor (Rs) produces is proportional to the current that passes through it. This voltage is contrasted with the reference voltage (Vref) by the Op-Amp. The voltage across Rs remains below Vref and the Op-Amp output remains low while the load current is within the typical range.
The voltage across Rs surpasses Vref if an overcurrent condition, such as a short circuit or an excessive load current, takes place. Consequently, the Op-Amp output increases. The MOSFET’s gate is driven by this strong output signal, turning it on and cutting off the current to the load.
- The circuit is ideal for a variety of applications because it is quite simple and affordable.
- Due to their low ON-resistance, MOSFETs reduce voltage dips across switches.
- Due of MOSFETs’ quick switching characteristics, quick response time.
The values of variables like Rs and Vref will change depending on the demands of the particular application. Based on the anticipated load current and sensitivity of the protection circuit, designers should choose suitable values. When using the circuit in high-power applications, suitable heat dissipation and power considerations should also be taken into mind.