I am already doing the area calculation of the current waveform. The second
method you suggest also seems quite good. I will try it when I get a chance.

Thanks for all your answers.

-Ismail


On 8/4/06, Gerhard Fiedler <lists@connectionbrazil.com> wrote:
>
> Mohamed Ismail Bari wrote:
>
> > May be I need to rephrase my second question.- Here is the scenario -
> >
> > I have a device that consumes 150mA when active and 500uA during sleep.
> > The sleep/activity happens quite fast and periodic. The current puleses
> > overshoots to about 300mA when the device activates.  I want to get a
> > good estimate on the power consumption accounting the current
> > overshoots. Is there a way for doing it?
>
> The "proper" way to do it is to integrate over the current.
>
> One quick and dirty form of doing that is to get a typical current form on
> a scope (if it is repetitive, this shouldn't be that difficult) and figure
> out the area under the curve. It is proportional to the power consumption
> (assuming the voltage is constant). This also tells you quickly whether
> the
> 300 mA spikes are relevant: if they are relatively short ("needle" shaped)
> pulses, the area is small and possibly negligible.
>
> Another form of doing that is to drive the unit from a large enough
> capacitor, through a voltage controller that has a known consumption. The
> voltage change at the capacitor is proportional to the integral over the
> current taken out of it. So you get that, subtract the consumption of the
> regulator, and get your device's consumption.
>
> Gerhard
>
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