Data Sheet

LT8350S

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Rev. A

20 of 36

Figure 29. Current Mode vs VIN/VOUT Ratio

Figure 30. Operation Region vs VIN/VOUT Ratio

(1) Peak-Buck in Buck Region (VIN >> VOUT)

When VIN is much higher than VOUT, the LT8350S uses peak-buck current mode control in the buck region (See

Figure 31). Switch C is always off, and switch D is always on. At the beginning of every cycle, switch A is turned on,

and the inductor current ramps up. When the inductor current hits the peak-buck current threshold commanded

by VC voltage at buck current comparator A1 during the (A + D) phase, switch A is turned off and switch B is turned

on for the rest of the cycle. Switches A and B will alternate, behaving like a typical synchronous buck regulator.

Figure 31. Peak-Buck in Buck Region (VIN>>VOUT)