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Shunt resistor at AD8218 input

Question asked by Jatin on Nov 19, 2012
Latest reply on Nov 20, 2012 by AnnaFeB

Hi,

 

Need to measure DC load current (approx. 0~10A range). Used AD8218 with shunt resistor of 6mOhm & 80mv internal ref. enabled. Attached its schematic. Such arrangement is considering ADC's max. available input range of 1.2V. [ (10A*6mOhm*20) + 80mV ] = 1.28V 

 

At 24VDC load voltage & defined load of 700mA, I can measure voltage drop across 6mOhm shunt resistor = 3mV (instead of 4.2mV in actual). Not able to understand why it is so? Am I missing something or is there any limitation like for R(shunt) min. required value?

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