Heteropolarity Turn-Off Absorption Circuit

Published:2011/5/5 1:39:00 Author:Robert | Keyword: Heteropolarity, Turn-Off, Absorption | From:SeekIC

The picture 1 shows the heteropolarity turn-off absorption circuit which has a capacitor in parallel with the switch. When the switch is conducted, the capacitor Cv discharges quickly through the switch V, which makes the switch's additional current large during the conducting moment, and this could damage the switch. To avoid this situation, the pratical shutdown absorption circuitis RCD networks. It is called heteropolarity turn-Off absorption circuit because there are diodes in it. The picture 2 shows the polarized snubber circuit -- application of RCD networks in buck converter, and it is in parallel with the switch. The compositionof the RCDis using a resistance Rv in parallel with a diode Dv, then take them in series with a capacitor Cv. The Rv's function is limit the Cv's discharging current when the swith is conducted, and also it transfers the energy in Cv to the resistance Rv to be consumed away. The diode Dv's function is making Cv be charged through the diode Dv when the switch is closed, and also the Rv coube be shorted by Dv.



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