The latest digital release of the Trilogy of Magnetics includes the following key improvements:

Over the years, engineers have found small typographical errors in McLyman’s original constants (e.g., the window utilization factor Ku or core geometry Kg). Updated versions include margin notes or corrected appendixes.

Critical Alert: If you download a PDF dated before 2005, check the ferrite loss graph on page 3-12. Older versions do not account for the square-wave excitation losses found in modern GaN (Gallium Nitride) inverters running at 500 kHz+.

Open the PDF. Navigate to the updated Appendix C: "Core Selection for Single-Ended Converters." Use the formula: [ K_g = \fracP_o \cdot T_on\Delta B \cdot K_u \cdot J \cdot K_f ] In the UPD version, the constant for K_f (waveform factor) now includes a note for squarewave vs. sinewave (critical for GaN).