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Hercules RMx electrical data ?

Other Parts Discussed in Thread: INA210

Good day I have a big question, I would like to know what the overall consumption of a Hercules RM57L and RM46 and RM42?

Datasheet indicated in 905mA to RM57Lx, this is almost 1 Ampere of current; this is real or referential.


Best Regards

Martin Valencia

  • Martin,

    It's a real spec number, but not  (EDIT) note that it is a max over the recommended operating conditions. 
    So that would be the max operating temp, max operating voltage, and a unit that is 'hot'.

    You probably won't easily reproduce this in your own testing, but you should design for it.

    Best Regards,

    -Anthony

  • Also, you can measure the core current on your RM57 launchpad by measuring the voltage on the node connecting R28/C31 labeled HERCULES_ICORE.
    R29 is 10 milliohms and the core current goes through this. If core current is 1A, then you would expect the voltage across R29 to be 10 mV.
    This is amplified through the INA210_DCK which is a precision instrumentation amp and has a gain of 200.
    So if you measure 0V on that node, the core current is 0mA. If you measure 2V on that node, core current is 1A.
    (and it's linear in between). I believe the resistor is 1% and the INA is about the same so figure you'll be within 2% or so with this measurement.
    The output is filtered but it's the filter pole is at about 7.8KHz. So you can try various algorithms and watch the current consumption per algorithm with a scope. I would expect you might see the current high while you are running your FFT and then go down between runs for example.
    Similar circuit is on the RM46 launchpad... -Anthony
  • Thank you very much for your quick response, the truth today was talking with a professor at the university and i was commenting on the performance of the new platform Hercules RM57L and we carry a great surprise to see the current consumption, our doubt born here.

    Hercules RM57L consumed much current, but hey I can now see that it depends on the algorithms that is running!


    on the other hand there is some low-power mode to the Hercules family, a way to put to sleep the processor?
  • Hi Martin,

    Yes, the device includes various low power modes but they are based on shutting off clocks.   This will cut down the power consumption due to switching, but there is another component called leakage that at the 65nm node is significant.   The RM57L datasheet is still product preview and is missing some of the data that is in other datasheets.  But look at the RM48 datasheet, and you can see the typical power consumption is listed at 260mA and max at 420mA -- at 220MHz.   There is an equation in the footnote that shows the effects of voltage, temp, and frequency on this number.

    If you take footnote 2, it says that in the maximum power consumption case, the 420mA number could be derated by 1mA/MHz with frequency.    So if you were to shut off all the clocks you may expect the current consuption to drop by 220mA.   That still leaves up to 200mA max due to leakage.  There's also equations in the footnote where you can plug in voltage and temp and further derate.    But it's going to be some # of mA,  not uA.

    -Anthony 

  • Thank you very much, I've seen the datasheet of RM48 and I noticed differences, recent data are very useful.

    Have a good day!

    Best Regards

    Martin V.