I am planning on using a difference amplifier IC much like the AD8206 to measure the differential voltage across a high side shunt in order to monitor the current.
I chose a differential amplifier over a current sense amplifier (CSA) IC because its more robust to large input differences, less sensitive to input filtering and I don't have a need for high speed current measurement so the lowered bandwidth is ok for me.
- The issue with differential amplifiers verse CSAs is that they attenuate the signal before feeding it into its internal amplifiers. Is this an issue? I don't fully understand the ramification for input signal attenuation. I get that its a reduction in amplitude so possible resolution?
- The CMMR is worse in differential amplifiers than CSAs. But why do I care? I am struggling to grasp the importance of CMMR in application. I know that in an ideal world an op-amp only applies a gain the differential between the 2 inputs and ignores the common mode. From my reading I've found [common mode voltage = (V1 - V2) / 2]. So High CMRR rejects the gain associated with that common mode voltage? Can someone illuminate the application importance for CMMR?
Thank you for your time.