I've decided to try measuring the current consumption of a battery powered gadget. The measured current is always less then 100mA. The voltage varies between 3.1 V and 1.8 V. I'm currently using an Uno to measure the voltage and I want to also measure the current. The Uno is powered from a USB hub (5.05 V).
I can use an instrumentation amplifier on another more permanent project so I've decided to try using one for this test.
Browsing Mouser, I settled on this instrumentation amplifier... http://www.mouser.com/ProductDetail/Texas-Instruments/INA126PAG4/?qs=sGAEpiMZZMuvJlO0BgfYbBOz9neZdvOf http://www.ti.com/lit/ds/sbos062a/sbos062a.pdf
Some things I like about it: The gain is in range (I believe I need 100 or 500 gain). The supply voltage is very versatile (1.35V to 18V). It appears to be easy to use (one external resistor to set the gain and two bypass capacitors). It's bread board friendly.
My plan is to power the amplifier from the Uno (5.05V). The input will be from a low-side 0.1 ohm shunt. Absolute accuracy is not important. I'm primarily interested in relative differences (e.g. if I change X what is the percent change in current consumption).
My problem is that I don't have a clue how to read the datasheet. I don't know which parameters might be a cause for concern, which parameters I can ignore, and which parameters indicate this is a good choice for amplifying a 0 to 10 mV signal to be fed into an Uno's analog input.
Any guidance about this (or any other appropriate) amplifier is appreciated.