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Could UCC27322 driver 13.56Mhz CoolMOS ?

ken-liang Jen
Prodigy 30 points

I test UCC27322TDGKREP  gate driver with function generator input and want to let it operate at 13.56Mhz  to drive 650V CoolMos  with Ciss= 5nF, which it need very High gate power 

after the test  I can only increase the frequency to 1.2Mhz and the IC start to work nonfunctional, if I increase  frequency more , the IC will break down.

So I found there's another Power pad package UCC27322DGN package which could operate at 3W power dissipation, rather than P package 350mW

So if I want to achieve  13.56Mhz is it Possible to use that  DGN package to realize?

  • 0
    Intellectual 930 points

    Hi Jen.

    Which MOS are you using?
    To evaluate your driver power dissipation you've to look much more to the requested Qg rather than your Ciss.

    I think that the switching frequency is really high...

    Which is your maximum ambient temperature?
    Probably, you will need to dissipate...

    Bye

    Paolo

  • 0 in reply to Paolo Reggio
    Intellectual 930 points

    Hi Jen.

    Looking to the CoolMOS DS, I found that probably you're using a IPW65R080CFD component.

    Well, you've 170nC of total gate charge to be supplied to the component.

    I don't know at which supply voltage you're working, however you've to dissipate at least 2.3052*VDD W, that seems to be really too much...

    You've two choices: select a different device with a lower gate charge requested, strongly dissipare your IC.

    Bye

    Paolo

  • 0 in reply to Paolo Reggio
    Prodigy 30 points

    I have Two questions

    1.What do you mean by Looking  Qg ?  

    Because what I thought is Reduce Ciss could reduce charging current ...but Qg?

    2.The Power dissipated equation from datasheet is totally absorb by IC?

    Determined by MAX IoDC current 0.6A  or power dissipation(350mW)? 

    Because calculated the Max Ciss  by  set Max Output DC Current seen from datasheet 

    Io(MAX) = 0.6 A

    ID = Ciss*15V*13.56Mhz = 0.6 A

    then Max Ciss = 2.29nF 

    But the Power = 2.29nFx15^2Vx13.56Mhz = 9W 

    or calculate by Pomax= 350mV = Ciss*x15^2Vx13.56Mhz  

    and get Ciss = 114pF....   which is Much Much less then 2.29nF

    So, How to calculate Max Ciss ? by current or Power ?  

  • 0 in reply to ken-liang Jen
    Intellectual 930 points

    Hi Jen.

    Qg is the total gate charge you have to supply to your MOS to switch on.

    Obviously, it is strictly related to the MOS capacitance, but it is much more easy to evaluate losses.

    All the current you have to supply to the MOS is drained from the driver, so multiplying your supply voltage for this current give you total amount of dissipation in your IC.

    Bye

    Paolo

  • 0 in reply to Paolo Reggio
    Prodigy 30 points

    Paolo, Thanks for answer .

    I think I know what to do ,  I'll order DGN package , which can reach max power dissipation of 3W 

    and decrease supply voltage from 15V to 12V , and find A Ciss less than 1.53nF 

    and enhance cooling for IC . It could probably reach I goal to drive 13.56Mhz at 800V blocking voltage MosFET.

    is there any more suggest that could probably help to my design ?