SLUA159 Datasheet, PDF (22/28 Pages) Texas Instruments – Zero Voltage Switching Resonant Power Conversion

APPLICATION NOTE
developed. Another, called Average Current
Mode Control is also a suitable candidate,
Fig. 30 - Error Amplifier Compensation
U-138
Summary
The zero voltage switched quasi-resonant
technique is applicable to most power conver-
sion designs, but is most advantageous to those
operating from a high voltage input. In these
applications, losses associated with discharging
of the MOSFET output capacitance can be
significant at high switching frequencies, im-
pairing efficiency. Zero voltage switching avoids
this penalty by negating the drain-to-source,
“off-state” voltage via the resonant tank.
A high peak voltage stress occurs across the
switch during resonance in the buck regulator
and single switch forward converters. Limiting
this excursion demands limiting the useful load
range of the converter as well, an unacceptable
solution in certain applications. For these
situations, the zero voltage switched multi-
resonant approach [14,15] could prove more
beneficial than the quasi-resonant ZVS variety.
Significant improvements in efficiency can be
obtained in high voltage, half and full bridge
ZVS applications when compared to their
square wave design complements. Clamping of
Fig. 31 - Zero Voltage Switched Forward Converter
3-350