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High side DC Current Measurment

I have been interested in alternative energy systems for a while now and as part of my 4th year project as Massey University I needed a way to measure DC current in the +ve side of a DC dircuit.

I investigated using a bunch of searate components and an opamp and found that the accuracy and drift would be significantly higher than using an all in one chip. The chip uses significantly less space on a PCB.
Out of several chips available the MAX472 is most suitable. It uses very little power in standby and is a bidirectional device. It had an output line and a sign line to indicate the polarity.
This device is available from RS Components for arround $12 in single quantities.

As A side effect of my project I am going to build up one on a separate board so I can use it to monitor the 12V system powering my amateur radio setup and its battery charging.

The circuit requires a shunt of only 30mR or less for reasonable current levels. I am basically using the circuit given in the datasheet with the values scaled approprieatly. The output can be scaled to interface to an ADC easily.