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dreaguns
Observer
Observer
388 Views
Registered: ‎05-30-2019

How does/can VCCINT use more current that the allowed max current per pins?

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I am using the XCZU4CG Zynq Ultrascale

UG583 (Ultrascale PCB Design) says that the absolute max current via pins is 20mA

The ultrascale only has 30 VCCINT pins

If (30 * 0.020 = 600mA) but XPE Power Estimator say that VCCINT requires more current (approx. 4Amps) then, 

How is the rest of the current going into the VCCINT domain or pins if they already met absolute max current?

dreaguns_0-1616430895455.png

 

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barriet
Xilinx Employee
Xilinx Employee
368 Views
Registered: ‎08-13-2007

For more information, see
https://www.xilinx.com/support/documentation/user_guides/ug583-ultrascale-pcb-design.pdf
e.g. page 49 -  "maximum possible Vccint current"
You'll notice that it depends on both the die device (e.g. ZU4) and package since both of those are possible limitations here.

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barriet
Xilinx Employee
Xilinx Employee
383 Views
Registered: ‎08-13-2007

The spec you referenced is how much current can be sourced or sinked from/to a SelectIO - on the outside I/O structure.


Which is a very different case than power (e.g. Vccint) or ground connection to the die on the package & substrate carrier itself.

barriet
Xilinx Employee
Xilinx Employee
369 Views
Registered: ‎08-13-2007

For more information, see
https://www.xilinx.com/support/documentation/user_guides/ug583-ultrascale-pcb-design.pdf
e.g. page 49 -  "maximum possible Vccint current"
You'll notice that it depends on both the die device (e.g. ZU4) and package since both of those are possible limitations here.

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joancab
Advisor
Advisor
360 Views
Registered: ‎05-11-2015

I/O pins --> 20 mA

Supply pins --> much more

dreaguns
Observer
Observer
328 Views
Registered: ‎05-30-2019

You mean to tell me that the 30 VCCINT pins on my Ultrascale can handle 52A ?

So that means 52A / 30 pins = 1.73 Amps per pin... sounds reasonable - thanks.

dreaguns_0-1616438692191.png

 

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barriet
Xilinx Employee
Xilinx Employee
320 Views
Registered: ‎08-13-2007

"You mean to tell me that the 30 VCCINT pins on my Ultrascale can handle 52A ?"
Yes - from a package & die perspective for this particular case (device & package)

That said, good luck dissipating ~44W (52A @ 0.85V - more if you consider I/O power, etc.) and being able to keep the junction temperature below max without a very impressive thermal solution.