I'm interested in using this part to sense the DC current going into a switching converter, and again, going out to a motor.

The spec sheet says that it will sense 0 to 20 amps, which is just right, because I should be using in the neighborhood of 10 amps, average. However, that current may consist of a pulse of 40 amps, say, for 20 uS, followed by dead time of 60 uS where no current flows. Would the ACS713 integrate the average current reasonably in this case, or will it clip once the current hits 20 amps?

 

sensitivity is 192mV/A
Power supply is 5V
Best case it can sense 26 A or (5/.192)

 

sensitivity is 192mV/A
Power supply is 5V
Best case it can sense 26 A or (5/.192)

Thanks for the reply. That makes sense for a steady 20A or even 26A, but I wanted to know what happens if my waveform has an average of 10 amps, but pulsed with peak amps going higher than (say) 26. There seems to be a filter capacitor in the circuit diagram, and I wondered whether the capacitor will correctly capture the average current?

 

I'm going to answer my own question, after a long time. I tried this experimentally (thank goodness, before committing to a PC board), and found that when they say 20 Amps, they really mean 20 Amps. You would think that you could sense 26 given the 5-volt supply, but in fact, the part goes very nonlinear at more than 20 Amps, basically clipping at that reading. So a 40 amp pulse at 25% duty cycle reads as if it was a 20 amp pulse at 25% duty cycle, or 10 Amps.

My solution is to go to an ACS723, which comes in a version that measures to 40 amps.