The LM5176 provides cycle-by-cycle current limit to protect against overcurrent and short circuit conditions. In buck operation, the sensed valley voltage across the CSG and CS pins is limited to V_CS(BUCK). The high-side buck switch skips a cycle if the sensed voltage does not fall below this threshold during the buck switch off time. In boost operation, the maximum peak voltage across CS and CSG is limited to V_CS(BOOST). If the peak current in the low-side boost switch causes the voltage across CS and CSG to exceed this threshold voltage, the boost switch is turned off for the remainder of the clock cycle.

Applying the appropriate voltage to the MODE pin of the LM5176 enables hiccup mode fault protection (see Section 7.4.2). In hiccup mode, the controller shuts down after detecting cycle-by-cycle current limiting for 128 consecutive cycles and the soft-start capacitor is discharged. The soft-start capacitor is automatically released after 4000 oscillator clock cycles and the controller restarts. If hiccup mode protection is not enabled through the MODE pin, the LM5176 will operate in cycle-by-cycle current limiting as long as the overload condition persists.