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685件の閲覧回数
cui1
Contributor II

Hello engineer!
I used the Shunt value for this parameter in the Vin of the look Current calculation company
These are the only shunt values I saw in the manual, but my actual Shunt value is 70uohm
What I want to know is if it's affecting my current measurements

cui1_0-1705053085682.png

cui1_1-1705053120315.png

 

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Q_man
NXP Employee
NXP Employee

the 1500A with the 100uOhm shunt results in 1500A*100uV/A = 150mV.

In the datasheet we limit the differential input voltage to 150mV:

Q_man_0-1705396756197.png

with 1500A on a 70uOhm will result in 105mV.

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cui1
Contributor II

cui1_0-1705054093890.png

 

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Q_man
NXP Employee
NXP Employee

Hi,

the idea of the shunt selection is to have a fixed 1mA/LSB of the actual ADC reading. We call this formating of the output value.

The ADC itself does always operate the same independent of the formating.

I suggest to use the standard configuration of 100uOhm, which has a 0.1uV/LSB result.

You shunt provides 70uV/A which would be 700LSB /A or ~1.43 mA/LSB.

Rgds
W.

 

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cui1
Contributor II
Thanks! But our maximum current value may reach 1500A, may I ask if 100uOhm has any effect?
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Q_man
NXP Employee
NXP Employee

the 1500A with a 70uOhm is no issue.

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cui1
Contributor II
Thanks! What I want to say is is it ok for the Shunt of 100uOhm to be at a maximum of 1500A? Is there any relevant calculation formula?
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Q_man
NXP Employee
NXP Employee

the 1500A with the 100uOhm shunt results in 1500A*100uV/A = 150mV.

In the datasheet we limit the differential input voltage to 150mV:

Q_man_0-1705396756197.png

with 1500A on a 70uOhm will result in 105mV.

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