This project isn’t a broad or theoretical overview; instead, it's a practical and focused venture: building a compact and energy-efficient switch-mode power supply (SMPS) capable of converting 220V AC mains to a clean, regulated 12V DC output, ideal for powering small home electronics, routers, or other embedded systems.
Introduction to the ICE2QR0680Z
Before diving into the project, it helps to understand the brain of our design. The ICE2QR0680Z is a high-performance, quasi-resonant flyback controller with an integrated 800V power MOSFET. Designed specifically for offline switch-mode power supplies, it offers a high level of efficiency, low standby power, and advanced protection features such as overload, overtemperature, and overvoltage shutdowns.This component is a perfect choice for modern DIY power supply designs aiming for energy efficiency and safety without needing complex external circuitry.
The Project Vision
The primary goal of this DIY project is to create a portable and reliable SMPS that:● Accepts a standard AC mains input (90V–270V AC),
● Outputs a clean 12V DC voltage at up to 1.5A (18W max),
● Incorporates safety features like short circuit protection,
● Is compact enough to fit into a small custom enclosure.
Such a power supply can be used as a standalone PSU or embedded in a DIY gadget such as a desktop audio amplifier, LED lighting system, or DIY NAS server. With the ICE2QR0680Z doing most of the heavy lifting, we can focus on making the design as efficient and safe as possible.
Planning and Component Selection
After selecting the ICE2QR0680Z as the core controller, the next step involves choosing other components that support its operation and meet our output requirements.Key supporting components:
● High-frequency transformer: Custom-wound ferrite core transformer designed for flyback topology.● Output diode: Fast-recovery Schottky diode, rated for 20V and 3A.
● Output filter capacitor: Low-ESR electrolytic capacitor (e.g., 1000µF, 25V).
● Input EMI filter: Common-mode choke and X/Y capacitors to suppress noise.
● Input rectifier and bulk capacitor: A bridge rectifier and a high-voltage filter capacitor (e.g., 400V, 47µF).
● Optocoupler and TL431: For feedback and output voltage regulation.
● Snubber network: Resistor, diode, and capacitor network to absorb switching transients.
These components are selected with the ICE2QR0680Z’s capabilities in mind, ensuring that they neither bottleneck performance nor compromise safety.
Building the Circuit Step by Step
1. Preparing the PCB or Veroboard
While some may choose to use a breadboard for prototyping, this project involves working with high voltages. Hence, it’s recommended to use a properly designed PCB or at least a veroboard with wide spacing between high-voltage sections. Special attention should be given to creepage and clearance distances between AC and DC sides.2. AC Input and Rectification
Start by routing the AC mains input through a fuse and varistor to protect against surges. Then, connect it to a full bridge rectifier to convert it into DC. After rectification, filter the voltage using a high-voltage bulk capacitor.Here’s where the ICE2QR0680Z comes into play. It operates on this high-voltage DC rail and uses a high-frequency switching approach to drive energy into the transformer.
3. Transformer and Switching
This step requires precision. The transformer should be wound according to flyback design principles. Typically, you’ll have a primary winding connected to the drain of the internal MOSFET (through the ICE2QR0680Z), an auxiliary winding for feedback and supply, and a secondary winding for the output.Once installed, the ICE2QR0680Z switches the internal MOSFET on and off rapidly, transferring energy through the transformer and controlling the timing to maintain efficiency.
4. Output Rectification and Filtering
The secondary winding connects to a fast-recovery diode, which directs the current into a large electrolytic capacitor. This capacitor smooths the high-frequency waveform into a steady DC output. This is where we get our 12V DC.Place a ceramic capacitor in parallel with the electrolytic capacitor to suppress any remaining high-frequency noise.
5. Feedback Loop and Regulation
Accurate voltage regulation is crucial. A feedback loop using an optocoupler and TL431 precision reference allows the ICE2QR0680Z to adjust its operation based on the output voltage. The optocoupler isolates the low-voltage output side from the high-voltage primary side.Proper tuning of the TL431 and feedback resistor network ensures that the output remains at 12V even under varying loads.
Enclosure and Safety Measures
Once the circuit is fully assembled and tested, it’s critical to enclose it in a non-conductive, ventilated case. Use nylon standoffs to mount the board and apply insulation to all exposed high-voltage traces.Install a small heatsink on the ICE2QR0680Z if needed, depending on thermal performance during extended operation. Although the chip is efficient, power losses can still generate heat under full load.
Also, consider integrating a thermistor or thermal cutoff fuse for additional protection against overheating.
Testing and Troubleshooting
Powering up the supply should be done carefully. Use an isolation transformer and an AC autotransformer (variac) if available. Start at a lower AC voltage and gradually increase while monitoring the output.Use a multimeter to verify that:
● The AC input is being properly rectified,
● The output remains steady at 12V,
● No excessive heat is generated,
● There is no audible whining, which can indicate instability or transformer resonance issues.
If the output voltage is incorrect, check the feedback loop configuration. If the unit shuts down under load, inspect the overload protection mechanisms. Often, it’s a simple resistor value or transformer winding ratio that needs tweaking.
Practical Applications
Once validated, this DIY SMPS becomes a highly versatile tool in your electronics toolkit. You can use it to:● Power a Raspberry Pi or similar single-board computer (with proper protection and regulation),
● Build a power supply for a custom audio amplifier,
● Supply power to a set of 12V LED strips for under-cabinet lighting,
● Charge 3-cell Li-ion battery packs via a DC-DC step-down module,
● Run your DIY IoT devices or sensors deployed around the home.
Because of the ICE2QR0680Z's high integration, the circuit stays compact and reliable, making it a great alternative to bulky or inefficient linear power supplies.
Reflections on the Build
This project is a powerful example of how modern integrated components simplify advanced electronic designs. In the past, building an efficient SMPS from scratch required deep knowledge of analog control systems and painstaking component matching. With the ICE2QR0680Z, much of the complexity is internalized — you just need to give it the right surrounding components and it does the rest.Of course, the challenge still lies in the transformer design and maintaining proper layout for EMI suppression. But these are manageable with some patience and attention to detail.
What sets this project apart is its balance of complexity and approachability. You’re not just assembling a kit — you’re crafting a piece of functional electronics that meets real-world power demands with reliability and precision.
Final Thoughts
Building your own switch-mode power supply using the ICE2QR0680Z is not just about saving money or customizing a voltage output. It’s about learning — about high-voltage design, EMI management, energy efficiency, and protection circuits. It's a gateway to deeper understanding of how modern power electronics work.More importantly, it gives you confidence. The next time you're working on a more complex DIY project, you won’t have to rely on generic adapters or scavenged power bricks. You’ll know how to build a clean, efficient, and safe power source tailored to your needs.
So gather your components, dust off your soldering iron, and begin crafting your own intelligent power solution — one efficient switching cycle at a time.
Disclaimer: This project involves working with high voltage and should only be attempted by individuals with adequate knowledge of electrical safety and circuit design. Always observe safety precautions when dealing with AC mains power.
US 13970 
GB 11241 
CA 9224 
AU 8640 
IE 4883 
BR 3500 
NZ 2600 
IN 1194 
