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Driving half-bridge with ADUM4223 using bootstraped power supply

Question asked by riar on Feb 4, 2013
Latest reply on Feb 6, 2013 by riar

Hi

 

I am driving a half-bridge with ADUM4223 and using a bootstrapping method to drive the high side switch. Just like a full-bridge, half-bridge circuit has a dc-capacitor. After start-up this dc capacitor is not connected to any dc-supply (i.e. floating).

 

I am unable to understand, how does this dc-capacitor gets charged to 12 V after start-up. Indeed, there is a 15 V isolated power supply that is turned on at start-up and is used to power isolated side of the gate driver. The bootstrapping capacitor is 47 uF and the dc-capacitor is 470 uF.

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