The D-CAP2 control mode is a variation of adaptive COT control mode which is popular in buck converters because of its simplicity and improved load-transient performance. There is an emulated ramp-generator circuit integrated inside the IC with D-CAP2 control mode. The ramp generator (ripple injection generator) emulates the inductor current information and brings this information back to the comparator. When the emulated ramp voltage and feedback voltage are lower than the reference voltage, the comparator output goes high to initiate an on-time pulse. The width of the on-time pulse (Ton) is constant, since it is calculated by the adaptive on-time generator based on the input voltage, output voltage, output current and frequency setting. The off-time relies on the voltage ripple, which has some variation during a line or load transient. As a result, the switching frequency is pseudo-fixed.