第3个回答 2008-04-22
bootstrap circuit?
在DC-DC CONVERTER的时候,如果high side swtich uses MOS,the source of this MOS connects to inductor,and this connection point is called phase node.
need to add a bootstrap circuit to maintain VGS>(VGS,on)for the MOS when the phase node voltage is switching.(Imagine, during the ON time, the high side switch is turned on, so the source voltage equals to drain voltage=Vdd or= Vin= the highest voltage in the circuit, simutanerously, to maintain the MOS on, Vgate has to be greater than Vsource and Vsource=Vdd now, so no voltage from the circuit is available now to apply to Gate of MOS, therefore, bootstrap circuit is to provide a Vgate higher than Vdd to switch on the high side MOS)