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Ok here is the problem. I have this circuit ( picture below ) and I need to design buck converter for it.

I was told by my mentor that I should calculate electric current this circuit will consume.

And I have no idea how to do that. I know that buck converter will convert from 72v to 12v that we will use to supply IC, optocoupllers and transistors, but how do I determinate electric current ?

Thanks in advance.

electric circuit

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  • \$\begingroup\$ Have you tried using Kirchoff's current law? \$\endgroup\$
    – The Photon
    Dec 17, 2014 at 22:46
  • \$\begingroup\$ Which supply are you asking about, VCC or VDD? In general, the current required will depend directly on how fast you're switching the power transistors. \$\endgroup\$
    – Dave Tweed
    Dec 17, 2014 at 23:13
  • \$\begingroup\$ Vdd supply. Could you give me some kind of formula or example , or something like that, to enlighten me a bit please. No I didn't try to use Kirchoff's law becouse I'm not sure how to use it in this example, I have only done it with simple circuits ( never had transistor in them ) \$\endgroup\$
    – gilley
    Dec 17, 2014 at 23:24

1 Answer 1

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You'll have to look at the datasheet for the IR2112. It should give you some idea of both quiescent (inactive) and active current consumption. Depending on how often Q1 and Q2 are switching, you may have to worry about their gate capacitance as well.

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