TPS5420/TPS5430 hiccup mode timing

There is no specific time for it.  TPS5430 family uses peak current detect for pulse by pulse current limit.  Pulse by pulse current limit tends to reduce on time.  The IC monitors for minimum on time pulses and will enter hiccup mode on the third consecutive minimum pulse.  As on time decreases, off time increases, so a sudden current surge may trigger the minimum on time an the first pulse.  The resulting longer off time allows the peak switch current to reduce more than normal.  In this manner it may be likely that there will be several non-minimum on time pulses between each minimum pulse during the initial over current.  It may take a relatively low impedance short on the output to trigger hiccup mode.