
Switch Mode Power Supplies (SMPS) are commonly used to power electronic circuits, but they can get damaged if overloaded. Over-power protection (OPP) prevents this by limiting the power drawn by the load, ensuring the SMPS operates within safe limits. Without OPP, excessive power can lead to overheating, damage, or even component failure.
The Problem :
When an SMPS powers multiple devices or high-current motors, the total power consumed can exceed the SMPS limit. For example, if a 12V SMPS rated for 5A drives a load consuming 7A, the excess current can overheat and damage the SMPS. Many commercial SMPS units come with OPP, but for DIY projects, adding external protection is necessary.
The Solution :
To prevent overload, use a shunt resistor to measure current and a comparator to trigger a cutoff when the current exceeds the limit. A MOSFET can disconnect the load, protecting the SMPS from damage.
Practical Example :
Consider an Arduino project where you control motors and sensors using a 12V, 5A SMPS. If the total load exceeds 5A due to motor surge currents, the OPP circuit detects this and disconnects the load, preventing SMPS failure.
Sample Calculation :
To calculate the shunt resistor value:
V=I×R
For a 5A current limit and a 0.5V threshold:
R=50.5=0.1Ω
A 0.1Ω, 5W resistor is ideal for this setup.
The comparator senses the voltage drop across the resistor and cuts power when the limit is exceeded.
Recommended Products :
MOSFET IRF540N – Ideal for load cutoff.
0.1Ω Shunt Resistor – Accurately senses current for overload protection.
Support our work and India’s innovation—buy from our Make in India site!
Written by smartxbrains
- Industrial Automation141141 products
- Cooling Fan44 products
- Indicators1111 products
- Plastic Casing66 products
- Sensor2323 products
- Sleeve and cables55 products
- SMPS88 products
- Solid State Relay Module22 products
- Switches1818 products
- Temprature Sensor11 product
- 3D Printing189189 products
- 3D printing118118 products
- Combination Kit4747 products
- Electronic743743 products
- Audio55 products
- Battery/Charger Accessories2828 products
- Capacitors6464 products
- Connector4646 products
- cooling fan11 product
- Diode3535 products
- Displays1212 products
- IC and Chips6565 products
- IOT and Wireless99 products
- Leds2424 products
- Microcontrollers55 products
- Modules/Shield7575 products
- MOSFET / IGBT1414 products
- Power Supply2525 products
- Resistors130130 products
- Sensors5959 products
- SMD2828 products
- Switches1414 products
- Transistors6868 products
- Wire and Cables1212 products
- Hardware3232 products
- Hand Tools1414 products
- Hardware Accessories1414 products
- Printing22 products
- RC Plane and Drone99 products
- Robotic147147 products
- BO Motors1313 products
- General Purpose DC Motors2929 products
- Motor Drivers88 products
- Robotic Wheels & Tyres1414 products
- Servo Motor2727 products
- Stepper Motors88 products
- Synchronous Motor11 product
- Science Fair Project7070 products
- Final Year Ready Project Kit11 product
- STEM KIT2222 products
- E Books88 products
Leave a Reply
You must be logged in to post a comment.