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Christian Ney

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Your quote about 32 phases being 8x2x2, that isn't how it is being done on the UP7, it is much simpler than that. It does limit max switching frequency to 1/4 that of the PWM, but officially the IR3563A ca do 1.2mhz, but unofficially IR told me it can be set to do 2mhz. However you don't run IR3550 over 300KHz anyways.

 

It is of course multiplexed, but not twice like it was in the past with the Z68X and P67A UD7.

 

The UP7 uses 8x quadrouplers, IR3599. The way it is done is that in the end you have four sets of 8 phase VRMs. So you have 32 phases and when each phase is fired from the PWM one quadroupler turns on 1 of its phases, then next cycle it will turn on another, next cycle another, and the fourth cycle another.

 

However this quadroupler chip also has the ability to turn on all 4 phases at 1 time, so that if the main PWM chooses to align all the phases then all 8 quadrouplers can turn on all 4 of their phases and total 32 phases. That is how GIGABYTE was able to get 2000W output out of that VRMs.

 

However you can run the UP7's VRMs without heatsinks, and that is because in normal operation it just turns on each phases 1/32 over four cycles, like a giant 32 phase VRM, however in essence there are still only 8 phases on each cycle, but every 4 cycles you turn on each of the 32 phases. So if you measure over 4 cycles then you will see each IR3550 turn on once, unless some transient occurs where the PWM might shut off or turn on more phases than normal.

 

That is what I got after i talked to IR and seeing how it actually works. Also with 32 phases you deff never want to run 4 on at one time, you just want 1 on at a time or else the switching loss would create a large amount of heat. When you get to so many phases, the loss from switching phases on is most likely larger than the loss from the work the MOSFETs do.

Edited by sin0822
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