The UCC25800-Q1 transformer driver automatically detects the dead-time after the switch-node voltage slews to within 1 V of the opposite rail. This slewing of the node is driven by the current flowing through the SW pin into the resonant tank at the end of the each MOSFET on-time. There must be sufficient current flowing through the SW pin at the end of the on-time to drive the SW pin voltage to the opposite rail. the voltage on the OC/DT pin programs the maximum dead-time. Even if the SW pin voltage crossing the threshold is not detected within the maximum programmed dead-time, the internal MOSFET switches on when the maximum programmed dead-time expires. Figure 8-7 and Figure 8-8 demonstrate the two adaptive dead-time operation conditions.

Figure 8-7 Adaptive dead-time operation without triggering maximum dead-time

Figure 8-8 Adaptive dead-time operation with maximum dead-time