Enter the Input Voltage, Output Voltage, Dropout Voltage, Load Current, and Quiescent Current into the LDO Calculator to find the Power Dissipation, Efficiency, Junction Temp, and Thermal Requirements for your linear regulator.
Number of Turns
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Peak Current
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Core Cross Section
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Magnetic Path Length
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Inductance Factor (AL)
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Wire Length Required
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E-cores have an open magnetic path making them easier to wind but less efficient due to magnetic leakage. Toroidal cores have a closed magnetic path providing higher efficiency and better magnetic shielding, but are more difficult to wind.
An air gap in the magnetic path reduces the effective permeability and inductance. However, it also increases the peak current capability before saturation and makes the inductance more stable with temperature and current variations.
Ferrite materials typically have relative permeabilities ranging from 500 to 10,000. Higher permeability materials provide more inductance per turn but saturate at lower current levels.
The maximum flux density determines when the core will saturate. Beyond this point, inductance drops dramatically and the inductor becomes ineffective. Typical ferrite cores saturate around 0.3-0.4 Tesla.
Wire diameter should be chosen based on current carrying capacity and available winding space. Thicker wire carries more current but takes up more space, potentially limiting the number of turns.
Peak current is limited by core saturation and depends on the number of turns, core cross-sectional area, air gap length, and maximum flux density of the ferrite material.
Different ferrite materials are optimized for different frequency ranges. Higher frequencies may require materials with lower permeability but better high-frequency characteristics to minimize core losses.
The AL value represents the inductance per turn squared (nH/N²) and is a measure of how much inductance each turn contributes. It depends on core geometry, material permeability, and air gap length.