Simple high-side current meter

Maxim has recently introduced a new integrated current meter IC called the MAX4173. It converts a current measured in the positive supply lead into a proportional voltage to earth. This can in turn be input into the A/D converter of a system.The MAX4173 allows a control microprocessor to measure and monitor the current consumption of electronic components. The main advantage of this new IC is that the voltage Vin on the supply lead to be measured may be higher (as well as lower) than the supply voltage VCC of the IC itself. This means for example that it is no problem to use a MAX4173 to measure the current on a +12-V line, even if the IC itself is connected to the +5-V or +3.3-V supply line of the processor. It is not necessary for both supply voltages to be the same, as with previous designs.