If the peak inductor current increases above the high-side current limit threshold, the device turns off the high-side switch and turns on the low-side switch to ramp down the inductor current. The device only turns on the high-side switch again if the inductor current has decreased below the low-side current limit threshold.

Note that because of the propagation delay of the current limit comparator, the current limit threshold in practice can be greater than the DC value specified in the Electrical Characteristics. The current limit in practice is given by:

Equation 3.

where:

• I_L is the inductor current.
• I_LIMH is the high-side current limit threshold measured at DC.
• V_IN is the input voltage.
• V_OUT is the output voltage.
• L is the effective inductance at the peak current level.
• t_pd is the propagation delay of the current limit comparator (typically 50 ns).