Flyback SMPS
Calculate key parameters of a flyback switched-mode power supply transformer.
One kind of switched-mode power supply is the Flyback SMPS, which functions by storing energy in a transformer during one portion of the switching cycle and transferring it to the output during another. It usually consists of a transformer, capacitor, diode, and switching transistor arranged in a specific configuration to effectively convert input voltage to the intended output voltage.
The main function of the Flyback SMPS is to convert an unregulated or fluctuating input voltage into a regulated output voltage. It rapidly cycles the input voltage on and off, stores energy during the off cycle, and transfers it to the output during the on cycle.
Understanding Flyback SMPS
Design and Operation
The flyback SMPS design encompasses two distinct operational phases:
- Primary Side — interfaces with the input power source
- Secondary Side — connects to the output load
Central to the flyback design is the transformer, which facilitates power transfer from the primary to the secondary side. A primary side switch — often a MOSFET or IGBT — is cycled on and off at a high frequency, typically ranging from 50 kHz to 200 kHz. This generates a high-frequency AC voltage on the primary side, which is subsequently transformed into a high-voltage DC voltage on the secondary side.
Advantages and Disadvantages
| Advantage | Disadvantage | |
|---|---|---|
| Efficiency | Often exceeds 90%, attributed to the transformer's role in voltage upconversion and current reduction | — |
| Size | Integration of a transformer enables remarkably compact configurations | — |
| Cost | Transformers are comparatively economical, rendering flyback SMPS cost-effective | — |
| Isolation | Provides galvanic isolation between input and output, enhancing safety and minimizing noise | — |
| Complexity | — | Requires a sophisticated control circuit to manage switching frequency and voltage regulation |
| Noise | — | High-frequency switching can lead to noise generation in certain applications |
| EMI | — | May produce electromagnetic interference (EMI), presenting challenges in EMI-sensitive applications |
Applications
- Consumer Electronics
- LED Lighting
- Telecommunications
- Industrial Automation
- Medical Devices
Conclusion
The flyback SMPS remains a favored option across numerous power supply applications owing to its high efficiency, compact size, and affordability. Despite drawbacks such as complexity and potential noise generation, it stands as a dependable and efficient solution for various application scenarios.
About This Calculator
This online Flyback SMPS calculator allows you to perform SMPS calculations and obtain figures such as:
- Tₘₐˣ — Maximum time
- Frequency
- Duty Cycle
- Energy per Cycle
- Power
- Current In and Out
Simply enter the voltage, transformer inductance value, and transformer VT product to get these values.
Inputs
Volt-time product of the transformer in volt-microseconds
Primary winding voltage in volts
Output voltage in volts
Transformer turns ratio (primary : secondary)
Primary winding inductance in microhenries
Leakage inductance of the transformer in microhenries (informational)
Forward voltage drop of the output rectifier diode in volts (informational)
Voltage drop across the switching transistor in volts (informational)