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ADG467 as protection for ADC input (output clamping voltage accuracy)

Question asked by mbeuret on Aug 19, 2014
Latest reply on Aug 19, 2014 by mbeuret

Hello,

I use an ADG467 to protect input ADC channel (ADS1247). I need to read low current ~30uA with an accurate ADS1247 ADC through shunt resistance. It is important that the leackage current is very low to don't impact the accuracy. That the reason I use ADG467 protector in place of diode againt overvoltage. Unfortunately the typical value don't limit the output at the good level (Vss+1.5V Vdd-1.5 Vtyp for Output open circuit conditions). ADC input current is about 1nA.

My question is: Have you any experience about the ADG467 repeatability. Do I have to expect no negligeable output limitation varation between ADG467 series ?

 

My result with VDD = 4,16V VSS= -4.10V => ADG467 output range =  -2.89V to  3.22V  (in place of-2.6V to  2.66V)

 

Thanks for your help

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