Hello,
We wish to monitor the current from a battery as in the schematic shown of a differential opamp with LT6220 opamp.
However, the LT6220 datasheet only gives the CMRR for Vin from 0 to 3.5V, and only when the supply to the opamp is 5V.
However, we have an 8V supply to the opamp, and the common mode voltage can go up to 4.8V.
Therefore, do you think our setup will be very accurate? We don’t need fantastic accuracy, but if the opamp output voltage is more than 10% away from what it should be, then that may be a problem.
LT6220 Opamp datasheet
https://cds.linear.com/docs/en/datasheet/622012fc.pdf
Please also find attached the LTspice simulation of it. (this shows no problem but I think the opamp models are idealised in the simulator, and have infinite CMRR over the entire input range, so the simulation cannot be relied upon.
We wish to monitor the current from a battery as in the schematic shown of a differential opamp with LT6220 opamp.
However, the LT6220 datasheet only gives the CMRR for Vin from 0 to 3.5V, and only when the supply to the opamp is 5V.
However, we have an 8V supply to the opamp, and the common mode voltage can go up to 4.8V.
Therefore, do you think our setup will be very accurate? We don’t need fantastic accuracy, but if the opamp output voltage is more than 10% away from what it should be, then that may be a problem.
LT6220 Opamp datasheet
https://cds.linear.com/docs/en/datasheet/622012fc.pdf
Please also find attached the LTspice simulation of it. (this shows no problem but I think the opamp models are idealised in the simulator, and have infinite CMRR over the entire input range, so the simulation cannot be relied upon.