VMOS tube switching power supply (1)

Published:2011/7/12 2:09:00 Author:TaoXi | Keyword: VMOS tube, switching power supply | From:SeekIC

The stabilized voltage power supply circuit which uses the VMOS tube as the switch device is as shown in the figure. In this figure, the VT5 is the VMOS power transistor, it is the switch adjustment device of this power supply; the L1 is the energy storage inductance; VD3 is the free-wheeling diode, VT3 is the MOSFET which can be used as the constant current source of VTl and VT2 to supply the 1mA constant current for the emitters; Cl is the input filter capacitance; C5, C6 and C7 are the output filter capacitances. In order to reduce the power consumption of the switching adjustment tube VT5 and improve the flip speed of it, this circuit uses the bootstrap network which is composed of the R5 and C4. When the VT5 is in the cut-off state, the source potential is 0V, the input voltage charges the C4 through the resistor R4 of the diode VD2, so the voltage of C4 closes to the input voltage.



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