The voltage sensed across the sense

The voltage sensed across the sense resistor generally contains spurious noise spikes, as shown in Figure 20.These spikes can force the PWM comparator to reset the RS latch prematurely. To prevent these spikes fromresetting the latch, a blank-out circuit inside the IC prevents the PWM comparator from resetting the latch for ashort duration after the latch is set. This duration is about 325 ns and is called the blanking interval and isspecified as minimum on-time in the Electrical Characteristics section. Under extremely light-load or no-loadconditions, the energy delivered to the output capacitor when the external MOSFET in on during the blankinginterval is more than what is delivered to the load. An over-voltage comparator inside the LM3478 prevents theoutput voltage from rising under these conditions. The over-voltage comparator senses the feedback (FB pin)voltage and resets the RS latch. The latch remains in reset state until the output decays to the nominal value.