Power & current measurment

Hi,

Spike on the resistor ... should not be, since it is mandatory to put fast capacitors at the VCC pin(s) of the microcontroller. (no resitor between capacitor and IC)

Thus I expect frequencies in the kHz region max. .. with low voltage ripple.

Klaus

KlausST said:

Hi,

Spike on the resistor ... should not be, since it is mandatory to put fast capacitors at the VCC pin(s) of the microcontroller. (no resitor between capacitor and IC)

Thus I expect frequencies in the kHz region max. .. with low voltage ripple.

Klaus

Click to expand...

Thanks for your reply.
Based on dynamic simulation in Innovus the peak of current is about 1.6ampers.
I want to measure this current and report it in a datasheet.

I do not have any capacitor near the IC that can measure the current peak.

Do you have any recommendations for an approach to measuring the spike current?

Thanks & Regards
Saati

Use infinite persistence mode on scope to get to peak values. If you
have color grading (frequency of sample occurrence) maybe turn that
on to get additional information on spike.


Another simple method, but takes longer to evaluate, is simple set scope for
level trigger mode, and keep advancing level until no more triggers occur.
But infinite persistence I think better method.

The value of infinite persistence, set your scope on AC, say 100 mV/box, infinite
persistence, and look at your supply rail. Usually an eye opener, eg. the pk-pk
noise levels on micro supply rails.

Make sure scope acquisition mode is at highest sampling rate, but
thats affected by spike rep rate.

Also use scope FFT to get a better idea of source of spike, eg. more detective
work.


Regards, Dana.