LM2594: current limit circuit

It does have cycle-by-cycle current limiting. 150kHz is the switching frequency. It can detect over current events like that. When internal FET current goes beyond the current limit value shown in the datasheet, it will turn off the internal FET before the end of the duty cycle. There will be a delay including the comparator delay and driver delay etc. I cannot find the delay time. The actual current peak will be higher than the comparator threshold due to this delay. The faster the current rising slew rate, the higher peak current. If the current rising slew rate is so high, such that peak current is about 20% higher than the current limit value shown in the datasheet, the LM2594 starts to foldback frequency to prevent the peak current going further up.

If you are doing a new design, I would recommend considering a newer device, such as LMR16006. Newer devices have better control method, protection features and higher efficiency.

Regards,

Yang