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I have a motor that's rated at 28A.

I want to monitor the power it's drawing so I got an ACS712 in its 30A variant. Knowing the voltage and multiplying by the output I get the power.

But what happens if the motor is stalled for whatever reason and the current goes above the supposed maximum of the ACS712? I tried to find some information about that in the datasheet but all that was stated regarding the measured current was a maximum transient of 100A for 100ms, which doesn't say quite a lot (at least to me).

Is the sensor going to be destroyed or is it just going to output the maximum regardless of how much above that the real current is?

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The answer is in the chip manufacturer's FAQ section about the chip.

The limit is how much the silicon heats up, so it depends on the ambient temperature.

At 85 C ambient temperature, it can take 40A for infinitely long.

Or 20A continuously at 150 C ambient.

It can also take short 200A pulses but they have to be limited so that they are short and do not happen too often so that the temperature limit is not exceeded.

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The various diagrams of ACS712 show an isolation between the high-current path (even using screw-down wire-in and wire-out terminals for the high current) and the Hall Effect sensor.

Thus the "risk of damage" at high currents will primarily caused by HEATING of the high-current copper? trace on the PCB.

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