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Typical vs Max power consumption

Audun Knudsrod
Intellectual 300 points
Other Parts Discussed in Thread: RM41L232, RM44L520

Hi, I have noticed in the data sheets for various Hercules controllers that some controllers have very small differences between these two numbers and some have big differences.

For example,
RM41L232's operational current is 135 typical and 145 maximum.

RM44L520 (120 MHz)'s operational current is 120 typical and 260 maximum, a huge difference.

I am asking this because I need a system with more than 32 kB of RAM (preferably 64k or 128k), but if I have to account for the maximum power ratings, my power budget will go through the roof.

So why are these numbers so different (max vs typical)? And which numbers should I take into account when specifying the power requirements?

  • 0
    TI__Guru 68950 points
    Audun,

    There is more logic (higher gate count) on the RM44L520 *AND* the spec is at 120MHz which is 50% higher than that of the RM41L232's spec of 80MHz. Both these factors contribute to the increase in powre consumption.

    There are some formulas you can use to derate the power consumption max # if you run at a lower frequency or temp.
    They are footnotes to the table in the datasheet.

    If all you need is more memory but run at 80MHz you'll still see a large increase but it won't be as large. You still see an increase because the leakage (power consumption just being turned 'on' and not switching) is fairly high at high temperature where these maximum numbers are specified. And the bigger die with more logic will have more leakage even if this logic is not being used.
    (it is still under power).

    -Anthony