DSP28075 hysteresis current using internal analog comparator

While I was using internal comparator to achieve buck circuit hysteresis current control, the output epwm suddenly disappears and caused current rising to a large value. The current and Vds waveform is attached to the question, the green curve represents the inductor current and blue curve represents the Vds of swtich.  I was keeping DAC value constant and the last step large current switching off is caused by OCP (Trip zone one shot).  Could someone can help? Thanks!