LM3481-FLYBACKEVM: Short circuit protection problem

Hi Team,

My customer used our LM3481's EVM to do short circuit protection and OCP function test. However, we can not see the reduction of switching frequency. Does this function only activate in non-isolated DC/DC design? Please see the test waveform as below. Pink color is switching frequency.

7.3.6 Short-Circuit Protection
When the voltage across the sense resistor (measured on the ISEN Pin) exceeds 220 mV, short-circuit current
limit gets activated. A comparator inside the LM3481 reduces the switching frequency by a factor of 8 and
maintains this condition until the short is removed.

Regards,

Polly Chung

RTW MM FAE