INA234: INA234

Hi Sergey,

inserting a shunt always generates an error caused by the voltage drop across the shunt. In many circuits this voltage drop can better tolerated when the shunt is mounted in the supply voltage line (high side measurement) and only the supply voltage is varying a bit than when the shunt is introduced into the ground line (low side measurement) and the whole circuit's signal ground is shifted by a varying voltage drop.

But:

When the shunt is mounted high side, the voltage drop across the shunt may be superimposed by a huge common mode signal which the current sense amplifier has to able to fully suppress. Because of this a current sense amplifier for high side measurement has to provide an outstanding common mode rejection of 100...120dB or even more.

When the shunt is mounted low side, on the other hand, the common mode signal is usually only very small and the current sense amplifier does not need a very high common mode rejection. Yes, in a low side current measurement even a simple OPAmp will do in most cases and no dedicated current sense amplifier is needed.

Kai