Can ACS-712 (5A) tolerate more than 5A of current?

Thread Starter

riemanndiy

Joined Jul 25, 2020
8
I currently have an ACS-712 (5A) (ACS-712 Datasheet), a Hall sensor for measuring current. In my project I'm running a dc brushed motor RS-550 (for maximum 30 seconds) that has an average current of 4.5A, but it happens that for very few seconds that it reaches 8A (not more).
Since I don't have the need to obtain a precise current measurement, my question is: Can the ACS-712 (5A) tolerate a current that peaks to 8A for very few seconds. I would like to not destroy/burn anything. Thanks
 

bertus

Joined Apr 5, 2008
21,364
Hello,

Did you read these passages in the datasheet:

The output of the device has a positive slope (>VIOUT(Q)) when an increasing current flows through the primary copper conduction path (from pins 1 and 2, to pins 3 and 4), which is the path used for current sensing. The internal resistance of this conductive path is 1.2 mΩ typical, providing low power loss. The thickness of the copper conductor allows survival of the device at up to 5× overcurrent conditions. The terminals of the conductive path are electrically isolated from the sensor leads (pins 5 through 8). This allows the ACS712 current sensor to be used in applications requiring electrical isolation without the use of opto-isolators or other costly isolation techniques.

Device may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature, TJ(max), is not exceeded.

Bertus
 

Thread Starter

riemanndiy

Joined Jul 25, 2020
8
The spec sheet absolute maximum ratings states that it will withstand a 100mS pulse of 100 Amps.
Well I've read that but I have no big experience in reading datasheets, so I asked for an advice. Since my case is approx 10x lower I_p; but 20x longer time than I_p; I think I can use it at a 8A for 2 seconds.. Am I correct?
 

crutschow

Joined Mar 14, 2008
27,213
Well I've read that but I have no big experience in reading datasheets, so I asked for an advice. Since my case is approx 10x lower I_p; but 20x longer time than I_p; I think I can use it at a 8A for 2 seconds.. Am I correct?
100A for 100ms is 10A-s so, assuming you can extrapolate using that value, you could run 8A for 10A-s / 8A = 1.25 seconds.
 

LowQCab

Joined Nov 6, 2012
552
It's only a matter of HEAT build-up,
the Circuitry will not be directly damaged by increased Current.
At 0.0012 Ohms, you won't have excessive Heat generated with ~8-Amps.

Calculate the Voltage Drop across the Sensing Conductor ........
Ohms X Amps = Volts
0.0012 X 8 = 0.0096-Volts

Now that you have the Voltage-Drop, Calculate the Watts that will be dissipated .......
Volts X Amps = Watts
0.0096 X 8 = 0.0768-Watts, that's roughly 1/13th of a Watt, not a problem.
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Kjeldgaard

Joined Apr 7, 2016
451
I mean the maximum continuous current must be at least 30 Ampere, whether it is the 5, 20 or 30 Ampere type.

And I base this on the fact that it must be the same Lead Frame for all three types, where they set the Primary Conductor Resistance to be 1.2 mΩ
 

Thread Starter

riemanndiy

Joined Jul 25, 2020
8
I mean the maximum continuous current must be at least 30 Ampere, whether it is the 5, 20 or 30 Ampere type.

And I base this on the fact that it must be the same Lead Frame for all three types, where they set the Primary Conductor Resistance to be 1.2 mΩ
I had just sort of feeling about this. Thanks for this important clarification
 
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