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Flyback SMPS

Computes the maximum on-time, switching frequency, duty cycle, energy per cycle, output power, input current, and output current for a flyback SMPS design from the transformer VT product, voltages, turns ratio, and primary inductance.

Inputs

Transformer VT Product(V×µS)

Volt-time product of the transformer in volt-microseconds

Voltage Primary(V)

Primary winding voltage in volts

Voltage Out(V)

Output voltage in volts

Turns Ratio

Transformer turns ratio (primary : secondary)

Transformer Primary Inductance(µH)

Primary winding inductance in microhenries

Transformer Leakage Inductance(µH)

Leakage inductance of the transformer in microhenries (informational)

Diode Voltage Drop(V)

Forward voltage drop of the output rectifier diode in volts (informational)

Transistor Voltage Drop(V)

Voltage drop across the switching transistor in volts (informational)

Results

⚠Voltage Primary must be greater than zero

Ton Max—µsMaximum transistor on-time in microseconds

Frequency—kHzSwitching frequency in kilohertz

Duty Cycle—Transistor duty cycle ratio

Energy Per Cycle—µJEnergy stored and transferred per switching cycle in microjoules

Power—WOutput power in watts

Current In—APrimary input current in amps

Current Out—ASecondary output current in amps