The ratio between Cup and Cdw on the VCR pin
should be determined by the maximum peak-to peak resonant capacitor voltage
waveform. These capacitor values needs to be chosen such that the maximum VCR
pin voltage peak to peak (occurs at the minimum operating input voltage and
maximum load current) should be always less than 6 V.
Lower Cdw results in a higher switching frequency
at a given Vcomp level.
The internal 2-mA current source is on during
dead time. If VCR voltage rails out to 0 V or +7
V, it means that the dead time is very long. In
case of ZCS detection, maximum dead time would be
150 us. In case of missing slew rate detection,
maximum dead time would be 1.1 us. The VCR pin
voltage can also rail out during burst. This is
usually caused if the boot capacitor too small and
the high-side gate does not turn on.