Selection of the blanking period is often empirical because it is affected by parasitics and thermal effects of every device between the gate-driver and output capacitors. The minimum blanking period prevents the current limit and PWM comparators from being falsely triggered by the inherent current spike that occurs when the switching MOSFET turns on. The maximum blanking period is bounded by the output rectifier's ability to withstand the currents experienced during a converter output short.
If blanking beyond the internal default is desired choose RBLNK using RBLNK (kΩ) = tBLNK (ns).
The blanking interval can also be chosen as a percentage of the switching period.