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I would like to estimate the current consumption of the FT2232H chip and I have some unclear issues with it.

In the chip's datasheet, it says the current for each voltage rail(except VCCIO).

enter image description here enter image description here

In Digikey and a reference design that I have found it says that the chip current supply is 70mA at a supply of 3 - 3.6V - I think it might be a mistake. because the datasheet says the same current supply for the VCORE voltage rail (Icc1)

Also, the datasheet doesn't mention VCCIO's current supply. Is it possible to calculate the current consumption without this parameter?

How did Digikey calculate it? enter image description here

I would like to calculate it by myself. How can I do it?

Thank you very much!

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  • \$\begingroup\$ Well VCCIO is basically just the current used to drive the IO pins, which depends on your setup. I would guess that its fairly negligible copmpared to the rest. I would say that the typical consumption (at 480MHz) is just 100ma. \$\endgroup\$
    – BeB00
    Commented Jul 11, 2018 at 15:54
  • \$\begingroup\$ how did you come to this estimation? is it mean that digikey's number is wrong? or not include the VCCIO current supply \$\endgroup\$
    – Mercury Avangburg
    Commented Jul 11, 2018 at 15:58
  • \$\begingroup\$ again, VCCIO is probably negligible. I'm guessing that the current is roughly just ICCPHY+Icc1. Digikey's number is really just a guideline, and should in no way be relied upon. The only reason it's there is to add utility to the parametric searching. In many cases, the digikey number will have no connection to reality. \$\endgroup\$
    – BeB00
    Commented Jul 11, 2018 at 16:01
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    \$\begingroup\$ So is it ok to say that the 3.3 voltage rail current consumption is Iccphy+Ireg+Ivccio =~310mA? \$\endgroup\$
    – Mercury Avangburg
    Commented Jul 11, 2018 at 16:06
  • \$\begingroup\$ No, that is incorrect. The regulator is the device providing the current to the other rails. The datasheet is saying that the maximum it can supply is 150ma, so icc1+iccphy cannot exceed 150ma (ivccio is not supplied by the regulator). Again, the 3.3v rail current consumption is most likely 100ma. \$\endgroup\$
    – BeB00
    Commented Jul 11, 2018 at 16:38

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As mentioned in the comments, probably 100ma.

ps: never rely on the parameters provided by digikey/fernell/etc, theyre just a rough guideline to help you search. Many parts have wildly incorrect listed parameters, or just dont have any.

edit: as chris says, remember that these are typical figures. They will vary as the chip does its stuff. Notice that no maximum current is given for the core, but we can infer what the maxmimum could be by assuming that the regulator will always be able to handle it, meaning that it must be <90ma (150-60). If the core does require more than this in normal usage, it would probably malfunction often, and no-one would buy it.

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  • \$\begingroup\$ There will probably be variation in consumption based on the pattern of usage by software. IO consumption will depend on what is being driven and the pattern of data. \$\endgroup\$
    – Chris Stratton
    Commented Jul 11, 2018 at 20:35

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