Estd turn ratio
A = Lp/Ls
f0(s) (kHz)
Ls (μH)
Lp (μH)
Cs (nF)
Converter parameters
Ls = XXX.xxx μH
Lp = XXX.xxx μH
Cs = XXX.xxx nF
n = XXX.xxx
Qs = XXX.xxx
A = XXX.xxx
f0s = XXX.xxx kHz


LLCDesigner is a program for helping to design LLC resonant converters. The user enters a power supply specification and then empircally tunes several values normalisation parameters to help determine appropriate resonant circuit components for their specification.

Description of operation

The screen is divided into two major sections: 1. Design specification, and 2. the Design characteristics tab.

The Design specification section is divided into several sections: 1. Power supply specifications, 2. Estimation of required turns ratio, 3. Normalisation parameters and 4. the Converter parameters.

For a specific design the user has to enter a power supply specification which consists of the anticopated maximum and minimum DC input voltage, the desired output voltage and the maximum output power. The Est turn ratio button estimates the required turn ratio
The user then must enter a desired series resonant frequency where f0s=1/(2π√(LsCs)), loaded quality factor Qs and an inductor ratio A=Lp/Ls. Clicking the Design Converter button determines appropriate component values and generates the steady control response.

The Charts 1, 2 and 3 tabs provides design information such as peak current and voltage information as a function of power output.

If you encounter any problems with the use of this software then please contact the author using m.p.foster@sheffield.ac.uk.


LLCDesigner is software for designing LLC resonant converters. No warranty regarding the accuracy of the predictions made with this program are provided. LLCDesigner is intended to be used as an aid for the designer and the user is advised to verify the results using independent means.

Copyright © 2008-2018 Martin Foster & Jonathan Davidson. All Rights Reserved. Permission to use, copy, modify, and distribute this software without fee and without a signed licensing agreement is strictly prohibited. Any warranties including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. The software and accompanying documentation, if any, provided hereunder is provided "as is". No obligation to provide maintenance, support, updates, enhancements, or modifications is made.

For further information regarding LLCDesigner, licensing or to report a problem with the software then please contact the author using m.p.foster@sheffield.ac.uk