I initially started out to ask if anyone has tried something like adding a parallel resistor to the current flowing through the ACS723 to bump the “base” current up into its operating range, but then I decided to just ask for some general suggestions as well. I develop one-off automated test fixtures used to test PC boards used in products. I’ve been trying for some time now to find a consistent, reliable source of an off-the-shelf product that allows me to measure sleep currents in the sub-100mA range for power supplies in the 12-24VDC range. Since these fixtures are often shipped to off-site manufacturers, and generally used and abused for 5-10 years or more, I’m trying to standardize on modules for which I can easily purchase replacements. I have yet to find anything in this category for very low current measurements. Most “low-current” measuring products only go down to 10’s of mA, and that’s generally closer to the high end of the range I need to measure. I’ve tried various INA219 and ACS723-based breakout boards from SparkFun, Adafruit, Phidgets, etc, but they all have the same issue of not reading extra-low currents. There’s stuff like the Nordic Semiconductor “Power Profiler”, but in addition to possibly not being available in the future, I believe it only supports Windows, and many of my fixtures use something like an Arduino MEGA or an Raspberry Pi to operate standalone. There’s the uCurrent Gold, but again, availability is a concern, and it still would take some external components to do what I need. Also, I would much prefer to read current on the high side, rather than the low side, since introducing anything between the device being measure and the circuit ground tends to cause more problems than it’s worth. Any suggestions would be most welcome. Thanks.
The galvanically isolated devices are usually great for higher current but not as good for low (high resolution) loads. I’ve found the LTC families (like LTC4151) to be better suited for that.