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(AD8418A)Is there any possibility that the output latch to Vs?

Question asked by donadona999s on Apr 4, 2016
Latest reply on Apr 12, 2016 by donadona999s


Hi !

 

I have an issue about AD8418A.

One of our customers is using AD8418A .

They are measuring the phase current of the motor.

The shunt resister is 0.3mOhms ,the output common level is 2.5V, Maximum current = 415A.

Also the output is pull downed 22kOhms to GND.

They are measuring the 3 phase as X,Y,Z.

But one of the AD8418A's(X phase) output goes suddenly High and system detect the Over Current and system goes down.

And after output goes high, the system stop the motor and the output voltage change to 3.6V after the motor stops.

I will attach the output signal waveform.

AD8418A.JPG

 

Only one of the AD8418A's output goes high and other are fine.

So I think this happens not because of AD8418A.

=> Maybe the PCB layout is something wrong

I'm also asking to our customer to measure Vs,REF.

They already measured Input and Output but the input look nothing wrong.

 

And at last year , the same customer tried to use AD8418A with the other motor system.

But at the BCI test, the output was same as this.(It look like the output latched).

=> they are using different Opamp now.


So my question is , is there any possibility that the output latch to Vs?

Kind of EMI or something.

If is AD8418A has this possibility , can you tell me the conditions.

example) frequency, input common level ,shunt resister,input current ...

 

Our customer and also I don't know why this happens

but I want help our customer to solve this problem.

 

Best regards.

Kawa

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