In buck mode operation, the converter starts a buck magnetization cycle (state II) with the internal clock signal. When the inductor reaches its peak current, the converter proceeds to the buck demagnetization (state III). With the next clock signal, the converter changes back to a buck magnetization cycle and starts a new switching cycle with sampling the peak current. As long as the duty cycle does not reach the minimum off-time, the current control remains in buck operating mode.

Figure 7-3 Inductor Current in Continuous Current Buck Operation