Hello,
My customer would like to have 10Mohm input impedance. So i use 2x 5Mohm in differential but If my understanding is right, the input impedance is 330K for low gain and 1Mohm for high gain. I'm wondering the this will have a too big impact on my reading? I know that i'm creating a voltage devider and this will reduce the voltage input on my ADC. But does the 5Mohm will be ok to charge the internal capacitor for the ADC reading?
thanks for your help
Hello Amuray,
Can you explain why they need a source impedance that large? Is this an intended voltage division effect where the voltage being sensed is 100s of volts and it needs to be divided down for the FSR of the ADC or some other reason? I noticed the 10M-ohm impedance is created from physical resistors in the schematic which tells me it isn't coming from the actual source or sensor connected to the negative and positive inputs.
If they do need a voltage divider effect, they can refer to the One-phase shunt electricity meter reference design using standalone ADCs TI Design where 100 V–240 voltage main lines need to measured https://www.ti.com/tool/TIDA-010036
Best,
-Cole
