Bootstrap technique for a multiple mode switching regulator

摘要

A multiple mode switching regulator with a bootstrap technique includes an inductor 20; a high side input switch 22 coupled to a first end of the inductor 20; a low side input switch 24 coupled to the first end of the inductor 20; a high side driver 34 coupled to a control node of the high side input switch 22; a low side driver 36 coupled to a control node of the low side input switch 24; a high side output switch 26 coupled to a second end of the inductor 20; a low side output switch 28 coupled to the second end of the inductor 20; a first bootstrap capacitor 30 coupled between the first end of the inductor 20 and a voltage supply node of the high side driver 34; a second bootstrap capacitor 32 coupled between the second end of the inductor 20 and a voltage supply node of the low side driver 36; and a first diode 40 coupled between the voltage supply node of the high side driver 34 and the voltage supply node of the low side driver 36. The two bootstrap capacitors 30 and 32 are employed on both sides of inductor 20 to provide gate voltage to high side input switch 22 through high side driver 34 in any mode of operation. This allows the regulator to work in three modes of operation without different external components or configurations depending on the mode.