Single Product

Details

1. Definition and Basic Concept

A flyback power supply operates on the principle of energy storage and transfer. Unlike conventional transformers that transfer energy continuously, a flyback transformer (technically a coupled inductor) stores energy in its magnetic core when the switching device is ON and releases that energy to the output when the switch is OFF.

2. Working Principle

1. Switch ON State

   • The input voltage is applied to the primary winding.

   • Current increases and energy is stored in the transformer’s magnetic core.

   • The secondary diode is reverse-biased, so no energy flows to the load.

2. Switch OFF State

   • The magnetic field collapses.

   • Stored energy is transferred to the secondary winding.

   • The secondary diode becomes forward-biased, supplying power to the output capacitor and load.

This ON-OFF switching happens at high frequency, enabling efficient voltage conversion.

3. Main Components

• Flyback Transformer: Stores and transfers energy

• Power Switch (MOSFET): Controls energy storage

• PWM Controller IC: Regulates output voltage

• Rectifier Diode: Converts AC pulses to DC

• Output Capacitor: Smooths the output voltage

• Snubber Circuit: Protects switch from voltage spikes

• Feedback Circuit (Optocoupler): Ensures voltage regulation and isolation

4. Key Features

• Electrical isolation between input and output

• Simple and low-cost circuit design

• Wide input voltage range

• High efficiency at low to medium power levels

• Compact size and lightweight construction

• Ability to generate multiple output voltages

5. Types of Flyback Power Supplies

• AC-DC Flyback Converter: Converts mains AC to low-voltage DC

• DC-DC Flyback Converter: Converts one DC voltage to another with isolation

• Quasi-Resonant Flyback: Improved efficiency and lower EMI

• Continuous & Discontinuous Conduction Modes (CCM / DCM)

6. Power Range

Flyback converters are typically used in power levels up to 100–150 watts, making them ideal for compact electronic devices.

7. Applications

• Mobile and laptop chargers

• LED drivers

• Adapters and wall chargers

• Set-top boxes

• Industrial control power supplies

• Consumer electronics

• IoT and embedded systems

8. Advantages

• Requires fewer components compared to other SMPS topologies

• Cost-effective for isolated power supplies

• Supports wide input voltage fluctuations

• Suitable for standby and low-power designs

9. Limitations

• Not ideal for very high-power applications

• Higher output ripple compared to other topologies

• Transformer design is critical for performance and safety

10. Protection Features

Modern flyback power supplies include:

• Over-voltage protection (OVP)

• Over-current protection (OCP)

• Short-circuit protection

• Thermal protection